Retrospective: Sea Trek (1991)

Introduction

Like many other thalassophiles, it can be a challenge to put your finger firmly on what inspired your love of the ocean and indeed, scuba diving. Those already familiar with my blog may recall I grew up by the sea: first Lee-on-Solent and then southeast Cornwall on the Rame peninsula. When I was a young child, my father dabbled in scuba diving when collecting specimens for his biology laboratory at school and my first encounter with a bucket containing a blue spiny starfish was most certainly a formative experience.

The equipment used to venture into the briny depths seemed almost as impressive as the idea of scuba diving itself. Not long after we’d moved to Cornwall in 1990, we were often visited by family friends Gavin and Petra, who would combine a visit to us with a dive trip out of Plymouth. I remember marvelling over Petra’s BCD and regulators as they dried out on our garden furniture, quizzing her over how they worked and what they did, feeling sure that one day, I too would possess the awesome power to breathe under the sea.

Sea Trek dropped in the middle of all this, airing on BBC 1 on October 7th 1991, and from the first episode I was transported to another world. The essential format was that presenters Martha Holmes and Mike deGruy would travel to an exotic diving location in each episode, framing a story around the unique habitats and ecology they encountered along the way. What made the series unique was the use of hard-hat style domes worn by the presenters. Gone were the bulky canvas suits and shoes however; these solid acrylic ‘bubble helmets’ as they were dubbed, allowed the presenters faces to be seen at all times and wired communications allowed Mike and Martha to interact with each other and the wildlife around them, with the genuine warmth of their relationship and their delight at their surroundings only serving to enhance the experience for the viewer.

Indeed, I was blown away; the fact that the bubble helmets had inherent practical limitations (more on that later) was neither here nor there: the experience immediately ‘clicked’ with me, a young viewer. I had of course been a fan of Wildlife On One and the numerous big-budget ‘Life’ series BBC Bristol had put out from the 80s into the 90s, but nothing grabbed me quite so much as this early co-production between the NHU and National Geographic.

It was perhaps unsurprising then, that in addition to ‘Ghostbusters’, The Land Before Time, and Home Alone, ‘Sea Trek’ was one of the few things I felt strongly enough about to beg my mother to buy on VHS from WH Smiths in Plymouth. I wouldn’t realise just how formative an experience it would be until the repeat viewings that were to follow.

Over the years I watched it intermittently. Typically, whenever I was poorly Sea Trek was always the VHS that went with me to whichever unfortunate babysitters that were lumbered with me for the day. With variously a packet of tissues, throat sweets or an emergency sick bowl, Sea Trek was inevitably what would take my mind off things until I felt well enough to be human again. It’s perhaps unsurprising, but there was something magically therapeutic about watching Martha and Mike dive into exotic locations, joking casually as they educated me about the marvels of the marine world. Unsurprisingly, I had all two hours and five minutes of it memorised before long, yet nothing save the threadbare magnetic tape giving out (it never did, thankfully) could stop my enjoyment of it. No program, perhaps apart the original Blue Planet (2000) has had such an effect on me since.

Amongst my first VHS videos, it remains the last on my shelf, retained long after I’d gifted away or thrown out my various X files and Red Dwarf VHSs, the last survivor of those analogue times. I’m glad I kept a hold of it; it was with me when I rather sheepishly stayed behind at Mike deGruy’s Pacific Abyss talk at the 2008 Dive Show in Birmingham. Some say you should never meet your heroes, but I’m so glad I got to meet mine in the form of Mike DeGruy. I almost choked up, but I managed to convey briefly (there was a huge line forming behind me) how much the series had meant to me as a kid. He was absolutely delighted to see the old VHS case, laughing “Oho! I haven’t seen one of those in a long time!” and signed the insert ‘Cheers- Mike deGruy’, before kindly standing for a photo with me. I have my now-wife to credit for spurring me on to hang back and talk with him, and in hindsight I’m so glad she urged me to take up the opportunity. Tragically, Mike died in a helicopter crash whilst filming in Australia in February 2012, so we were robbed of any more from him. Indeed, I feel so strongly about his work and Mimi’s deGruy’s documentary Diving Deep: The Life and Times of Mike deGruy I’ll probably end up following this up with another blog about it at some point.

Back to Sea Trek. It was some time later that I added Martha Holme’s signature to Mike’s. I had also retained a copy of the hardback volume Martha wrote and co-researched to accompany the series. I resolved to try and get in touch with her and see if she would sign my copy. Like Mike, Martha had gone on to participate in the seminal Blue Planet (2000) and following on from her work presenting she is now an incredibly respected producer of programming, not limited to natural history. It was around the first lockdown in 2021 that I contacted her office at Plimsoll productions, but my attempts not to sound like a nutter obviously fell flat as the office misunderstood my request as a stalkerish attempt to divulge her address. I gave up hope until several months later, when to my surprise Martha herself read my email, realised it was just mail from a fan (albeit from perhaps older than typical fan!) and messaged me back to say she would happily sign my book. I’m most grateful to both of them -and not just for indulging my personal nostalgia- but for teaching me so much about the sea and its creatures through this series and their remarkable careers in natural history broadcasting.

Thanks for sticking with me through my musings so far- what follows is a production credit and commentary on each of the episodes below. I’d quite forgotten, but I did actually transfer a copy of my original VHS into mp4 some time ago, obviously fearful of further degradation of the magnetic tape. There’s an obvious drop in SD quality (these being the heady days of analogue recording) and a few periods of faint buzzing from some electrical interference once or twice in the two hours and five minutes runtime, but it’s otherwise complete and as broadcast. I’m really in two minds about whether to share this online via youtube, as it’s obviously not my own content, but given the passage of time it seems impossible it will ever be made available elsewhere (believe me, I’ve looked). It also seems such a shame that so much of the gorgeous cinematography of the remarkable Peter Scoones, much beloved by BSoUP, is left on a shelf somewhere to degrade. I’ll think on it, but for now the poor imitation below will have to suffice:

Production Credits:

Presented by Martha Holmes and Mike deGruy

Series Producer: Robin Hellier

Cinematography: Peter Scoones

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Episode 1: Galapagos

The first episode opens with a gang of young sea lions whirling in the temperate water, as we hear Mike (MdG) observe:

‘It’s amazing how gracefully they move, and their ability to manoeuvre is unsurpassed – I’ve never seen an animal able to make such tight turns’

Martha (MH) responds:

‘I’ve never seen an animal underwater come so close and have such a playful nature.’

Both interact with the seals, turning about as the inquisitive animals twist and barrel about them, often coming between the pair and close to their hard acrylic helmets:

‘It’s hard to remember you’ve got an acrylic dome protecting you when they come so close – especially when they open their mouths!’ (MH)

Back on the surface, the camera pans to reveal the dive boat at anchor from the perspective of the shore. Mike and Martha introduce the Galapagos to camera, citing Charles Darwin’s fascination with the fauna of the islands. They stress that they are here to explore the marine diversity and the ‘Unusual and sometimes bizarre concentrations of animals’ (MdG) in these islands off the coast of Ecuador.

Delighted by the sea lions, the two are quickly back in the shallows with them, resolving to save the more challenging dives until later in the programme.

‘It’s like they’re young children being very mischievous.’ (MH)

…and when they start chewing on Peter Scoones’ audio cable:

‘If we vanish it’s not our fault, we promise!’ (MdG)

The crew has not gone unnoticed however, and it isn’t long before they’re inspected by the resident beachmaster:

‘Oh look, here comes a bull; this could get interesting.’ The pair explain that a single male jealously guards a harem of female sealions from male competitors, going so far as hassling divers approaching them to close. Sure enough, he glides by to display his considerable size before baring his teeth:

‘I’ll bet that was a warning.’ (MdG)

‘I’ve heard the way to put off a bull is to clap really loudly, but I’m not sure that works underwater, does it?’ (MH)

The scene then shifts to the island’s famous population of marine iguanas:

‘They may look prehistoric, but they’re very efficient feeders’ (MH)

Martha explains how their temperature can fall off by as much as 10 degrees centigrade as they forage amongst sunken rocks for the lushest seaweed:

‘Hungry or full, they must crawl out to soak up more of that equatorial sunshine.’ (MH)

Mike is then pictured in the midst of a shoal of thin silvery fish, intercut with scenes of waves breaking on the rough surface. He explains the Galapagos cause an upwelling in both warm and cold ocean currents, bringing nutrients to the surface but keeping the sea unpredictable.

Next, we cut to some ‘Surprising residents’ (MdG): Galapagos penguins in the northern extreme of penguin range.

Martha explains:

‘Penguins are timid, to swim with them requires a great deal of patience’

Mike adds that the only times they were able to get close were due to the ‘promise of a meal’

‘Faced with a school of shimmering fry, they have to home in on one fish to be sure of a meal.’ (MdG)

We then cut to the shallow-water coral gardens, and Martha explains how fish first colonised the islands. Moorish Idols and butterflyfish are shown, alongside predators such as the mottled adult Leatherbass and its smaller striped juvenile colouration.

Next, Mike and Martha scour the ledges and steep cliffs, themselves the sides of volcanos, for turtles. ‘Layer upon layer built these magnificent islands’ (MdG). They find a turtle, but as Martha predicts, it warily swims away.

Back in shallower water, they swim over a spot where the seabed is literally fizzing with bubbles of water percolating up from the floor. Martha explains the gas is escaping from a magma chamber directly beneath them -indeed one that could blow up at any minute! Unable to communicate the sensation of swimming suddenly into bath-temperature water, they hold a thermometer above the sea floor. It quickly reads past 120 degrees Fahrenheit and Mike pulls it away for fear of cracking the glass and releasing the poisonous mercury.

Back aboard, the sea lions are at it again, and the team welcome an invasion of young sea lions covering their tender and frolicking under the hull of their boat.

‘This is what happens when mom’s away’ Mike chuckles as the pair once again reflect on the playful nature of these younger animals, left in the care of an older sibling whilst their parents hunt.

‘Their sense of play is probably a lot more than meets the eye… learning skills that are vital for later life’ (MdG)

Heading back out to explore the caves around the island, Martha reflects on the variety of life:

‘It seemed we were to find something new every dive.’ (MH)

 Massive shoals of fish prompt her to comment on the strength to be found in numbers. The isolation of the islands have prompted several species to become endemic, evolving distinctly from their ancestors to form new species. These include the native groupers and the Galapagos fur seals. In comparison with the sea lions, Mike and Martha reflect on the fur seals’ more reserved movement, prominent eyes, rear fins and protruding ears. Martha explains the population were nearly hunted to extinction for their much-prized fur coats, the population inevitably crashing. This left a few individuals to rebuild the population up to it present-day protected status.

Rounding a corner, the pair wait in anticipation of a school of passing hammerheads, which oblige albeit from a distance frustrating for Mike, who wishes he could get closer.

‘… and what about that head!?’ (MdG) he exclaims as the two discuss the evolutionary advantages it confers on hammerheads hunting prey concealed in the sandy seabed.

Finally, the two swim into another huge underwater cave, finding their lights glancing off the silver sides of massive shoals of fish. Reflecting once again on the fame of the land animals of the Galapagos, Mike closes out the episode with the observation:

‘The underwater world is equally unique… I eagerly await the opportunity to return to this fantastic sea of surprises.’

Episode 2: Caribbean

In the second episode, as the intro fades out stingrays swamp the camera. Mike and Martha, clad in swimwear, stand waist deep in crystal clear water with rays bumping into and flapping up at them. Martha is delighted and alarmed in equal measure:

‘Are you sure this is quite safe?’ she asks Mike.

‘No, I’m sure it probably isn’t.’ he guffaws.

Aboard their boat again, they are philosophical as they sit near the swim platform gazing at the flood of flapping rays. ‘Every bit as strange or even stranger than anything to be found in science fiction’ (MdG).

He continues this train of thought as, bubble helmets on, they’re back out on the Gran Cayman sand flats. Mike opines:

‘Sometimes I feel more like a star trekker than a sea trekker wearing this helmet’ (MdG)

Martha looks about the cratered sea floor, the grooves clearly once occupied by the large rays:

‘The craters make this place seem more like the surface of the moon’ (MH)

Mike calls out ‘Look, here they come!’ and sure enough, as the camera switches over the shoulder of Mike and Martha, we see ‘a whole squadron of them’ (MH) gliding out of the blue in their direction. Mike explains:

‘Imagine a shark that has been flattened out- that’s really what these are.’ (MdG) The pair reach out to touch the approaching forms as they continue to talk through their biology to camera:

‘Stingrays are famed for their sting -ow!’ (MH) she exclaims, apparently on the receiving end of a prickle. Not to be outdone, Mike flattens his palms either side of another stingray’s tail, and whistles as they glide the length of the barbed tail, apparently without harm to himself.

Away from the flats, out on the reef, we cut to Martha tentatively enticing a moray eel out of the reef with the promise of a meal. Remarking on its poor eyesight, she seems happy to let it escape with its lunch unmolested, and all her fingers intact. She the talks through some of the other inhabitants of the reef, including eye-catching angel fishes, of which 90% of their diet is made up of sponges.

This segway lead us to Mike crouched over the rim of an immense barrel sponge, which he explains can filter up to 400 gallons a day, it’s constituent organisms each working in harmony within a larger whole. Nearby, a spotted eagle ray glides by the underwater cliff-edge.

‘I’ll stay up here and leave you with your fans’ puns Mike, as Martha explains the biology of gorgonians and sea fans.

Sometime later, over the edge of the drop-off, hovering in open water, Mike explains the bubble helmets limit them to a depth of around 100 feet (30m):

‘But Martha has overcome this limitation in a most enviable way!’ (MdG)

From the top of the frame a deep-sea bathysphere drops into shot.

‘I can’t believe I’m in this thing!’ Exclaims a delighted Martha.

‘I can’t believe you’re in there and I’m out here’ jokes DeGruy, famous for both his lifelong love of submersible technology and skill as a pilot. He lingers only to disconnect the coms tether that facilitated their exchange ‘You’re out of here!’ (MdG) and the submarine falls silently into the blue twilight with Martha gazing through the spherical dome. They pause at the 150-foot mark to note the shelf that extends around Grand Cayman before dropping into darkness at 600 feet. On the sea bed at 900 feet (near 300m) Martha explains the delicate dust and silt that covers most things is ‘marine snow’ composed of deceased biomatter. Marvelling at the experience she observes once again ‘It really is like flying across the surface of the moon.’ (MH).

The Sea Trek crew travel north to the Bahamas, where out in open water, Mike teases sharks by lowering a hydrophone into the depths. In voiceover, he explains sharks are particularly attracted to low-frequency sounds, such as emitted by a fish in distress. Almost instantly, silky sharks glide out of the depths and bump the hydrophone, apparently confused at the absence of the ‘easy meal’ Mike now feels guilty for teasing them with.

The scene shifts to Mike and Martha descending down to the silkies: ‘Speaking of easy meals – are you ready for this one?’ he laughs as they approach the befuddled sharks. What follows is a discussion of shark biology and reproduction strategies. Mike and Martha explain that younger sharks lead difficult lives evading being eaten themselves, with juveniles tending to stick close to the reef as a ‘reference point’ (MH) before beginning a pelagic life out in the open ocean. Mike points out that most sharks exhibit some form of counter-shading, with a paler underside blending with the surface and the steely grey top making them similarly harder to detect from above.

We shift closer in to shore, with Mike and Martha peering in to sea caves, their lights again reflecting schools of fish hiding during the day. Predatory tarpon with rather serious underslung jaws lurk beneath an underwater archway, awaiting the coming dusk.

As night begins to fall Martha narrates:

‘When one lot of animals are sleeping, another are feeding. Few animals work both shifts.’ (MH)

Mike holds out his torch beam and demonstrates the myriad of tiny creatures dancing in front of the lamp. He explains the principle of deepwater migration; the huge biomass of plankton that avoids the shallows by day coming up from deep water to feed at night.

Whilst almost all-night prowlers of the reef are predators, Martha holds in her hands one of the few delicate herbivores; a black spined sea urchin propelled on its hydraulic spines.

Mike directs the camera to a brain coral with its feeding polyps extended. During the day these would be a tempting meal for passing fish, but at night it is safe for them to extend a snatch a supplementary meal from the current. Similarly tucked into the reef, the pair find a parrotfish newly ‘abed’ and not yet in the mucus bubble they secrete to mask their scent from predators as they rest.

Mike explains that about an hour before sunrise the ‘shift’ changes and the daylight creatures emerge from the reef to go about their business.

The next dive takes us out to a sandflat frequented by a pod of spotted dolphin in blazing sunshine. Mike and Martha delight in interacting with the dolphin – necessary to ensure their continued presence- and they observe the whiter spots atop the dolphin yielding to darker spots on the underside, with the younger animal having no discernible spots at all.

Martha notes the importance of touch in their communication, with Mike commenting that echolocating clicks and whistles are near-constant, with the animal’s posture used to change the context of the same.

Martha explains that they commonly use their echolocation to hunt flounder out on the sand flats, with some clicks estimated as powerful enough to even stun or disorientate a target fish, impeding its escape. She then explains that each dolphin has its own unique whistle ‘name’ by which it is known to the pod, with individuals called out by this signal.

Reinforcing the importance of touch, the two observe how baby-sitting dolphins maintain close contact with calves; rubbing pectoral fins and even guiding the young’s direction of travel by hooking their tail fins around the dorsal fin of the younger animal.

Unable to resist the urge to interact with the dolphins fully, Martha and Mike abandon their bubble helmets to re-enter the water with snorkels. The episode ends with Martha’s voiceover as the pair dive and spin around the dolphins as Peter films:

‘It was a remarkable encounter, and one which we knew would be hard to beat.’ (MH)

Episode 3: California Kelp Forests

The episode opens to the ecstatic whoops of surfers, riding waves on the California coast. We cut from them to forests of lush kelp with Martha stating ‘It’s fun out there but it’s beautiful down here.’

Mike follows up with a brief description of the bubble helmets, suggesting that at least at one point this might have been the intended opening episode for the series.

As we follow Mike and Martha through the kelp forest, analogies are easily to hand:

‘A comparison to a tropical rainforest and a kelp forest is easy’ says Mike, as he begins his ascent through the base of the canopy. Half way up he is replaced by Martha, presumably to avoid the risk of a rapid ascent: ‘Hah, it bears fruit! Hello Martha!’

Back on the surface, the pair approach a nursing sea otter and her cub, a scrawny ball of fluff cradled gently between her paws.

Whispering so as not to disturb the pair unnecessarily, Mike breathes:

‘God… that thing looks brand new, doesn’t it?’

And as the mother spins to attend to its coat, temporarily parking its cub in the frigid water next to it:

‘Backbone made of rubber!’ (MdG)

The cub waits as Mike and Martha anthropomorphise its impatience with its mother, occupied with cleaning her thick coat. More shots of sea otters show them preparing to sleep for the night, deliberately entangling themselves in the upmost fronds of kelp to avoid drifting off in their sleep.

The action then shifts underwater, with a bubble-helmeted Martha and Mike watching an otter push off from them to scrabble about for shellfish in the cold water. They explain that they have no blubber, remaining very active to keep up a core temperature, eating up to 40% of their bodyweight each day. With often reduced visibility, they are heavily reliant on sensitive paws and whiskers.

‘Mission accomplished, it’s back to the surface, armed with a rock and clam.’ (MH)

The camera looks on as the sea otter energetically sets about the clam with its stone, successfully breaking into the flesh within. Martha explains that whilst the sea otters are beloved by many, some fishermen consider them a pest and threat to their livelihood.

The action shifts to the Channel Islands 30 miles offshore, where the giant kelp is in such good condition it is now part of a national park.

Starting once more at the base of the kelp, Mike explains that it can grow up to two feet a day. Martha explains how important it is for the algae’s survival to happen upon a reliable holdfast. Too flimsy, and the kelp risks being washed away as it develops. Mike examines the ‘stipe’ the tether of multiple strands that make up the ‘trunk’ of the kelp. The kelp faces numerous problems as it grows, mostly from colonising organisms keen to grow on its surface, Senorita fish largely keep these in check in exchange for shelter amongst its fronds. Elsewhere kelp fish disguise or advertise their presence, like the bright orange Garibaldi. Blacksmiths pick plankton from the water column in between the occasional clearings that give a sense of scale to the forest. Important nurseries for juvenile fish of all kinds, Martha explains the forests are also home to the sheephead fish, unfortunately prized by spear fisherman. Over-predation by humans has in the past, led to an increase in the number of the kelp-eating urchins the sheepheads keep in check, leading in turn to ‘urchin barrens’ where the kelp has been eaten clean away.

Mike spots a bat ray leaping out of the sand ‘They do know how to fly!’ (MdG) and more footage of the rays shows them gliding through the forest, resting on the seabed, before taking to wing again.

The scene shifts to the reef, where Mike gently plucks a juvenile horn shark from seabed to explain how it got its name; pointing out the two horns atop and behind each dorsal fin.

Martha explains how the screw-like structure of the horn shark egg case allows mother horn sharks to grasp the egg case with their jaws and lodge them securely in rocky crevices.

The scene shifts to the flats, where Mike has found the outline of an angel shark buried in the sand. ‘It’s no angel’ (MdG) He wafts the sand covering from its back to reveal its perfectly camouflaged mottled skin beneath, and then tentatively proceeds to lift the creature from the substrate, tail first, almost bodily out, until with an explosion of movement it darts away.

Closer into shore, in some of the small bays the pair happen upon a gathering of female leopard sharks. Snorkelling owing to the terrain and not to disturb the skittish sharks, Mike and Martha surface to speculate as to what the sharks achieve by congregating this close-in to shore. Mike observes that they are not feeding, speculating they are taking advantage of the warmer water to speed up their metabolism and aid in the gestation of their young, yet Martha is unconvinced, making the point that research has only just begun on these gatherings.

The duo returns to the flats on a night dive to find crawfish scuttling out from their hidey-holes, and Martha makes a magnificent find hinted at earlier: a tiny hatchling horn shark, still ensconced in its drill-shaped egg case with yolk-sac attached. Martha carefully returns it to the spot on the reef she found it as Mike muses on the idea of returning to the same in in sixth months to see if it had hatched out fully from the egg case.

The focus then shifts to the open ocean and a drifting kelp ‘patty’ that has broken free from the main forest. The young fish that were sheltering within it have accompanied it out into open water, but now they are joined by more pelagic species seeking temporary respite in the blue desert. It’s here Martha sees her first mola mola, the immense ocean sunfish, as it sifts particles from the open ocean.

Back aboard, the music becomes more dramatic as chain mail shark suits are donned in addition to the bubble helmets and a cage is lowered into the water. We soon know why: after baiting for several hours the pair are about to enter the water with several large blue sharks. Whilst the sharks are relaxed and the cage seems unnecessary, several of the larger fish do pass close by Mike and Martha, with one gaping its mouth round Martha’s bubble helmet. Mike identifies a female shark from the clear bite marks ahead of her dorsal fin and remarks how female sharks have thicker skin for this express purpose.

‘Look at the size of those pectoral fins! Everything about them seems long.’ (MdG)

Like many people witnessing these sharks up close, the colours stun Mike and Martha:

‘The dappling of sunlight across their backs… it’s amazing.’ (MdG)

Martha, perhaps well placed given her recent encounter, observes the shark’s capacity to roll back membranes to cover their eyes prior to contact. Clearly affected, Martha closes out the episode by reflecting on this last dive in the Bahamian blue sharks:

‘Humbling… we felt graceless and awkward by comparison’ (MH).

Episode 4: Great Barrier Reef

The episode opens with Martha’s first sighting of a loggerhead turtle over the reef, where the pair remark on the elongated head they are named for. Unlike their Galapagos turtle encounter, this loggerhead is not alarmed by their presence at all – in fact it makes a beeline straight for them, inspecting them both before swimming directly at Peter’s camera.

Nighttime and on shore, green turtles clamber up to lay their eggs. Kneeling quietly by a laying female, Martha and Mike explain they take between 14-15 years to reach sexual maturity, the exhausting process of egg-laying then split between what can be 8-year intervals. The leathery soft eggshells remain intact as they land upon one another, with the mother then beginning the process of gently burying them with her large rear fins. Mike jokes they’d best leave before being buried along with the egg clutch as Martha narrates the turtles laborious crawl back to the water’s edge:

‘Their eggs safely buried; the exhausted turtles must get back to sea as fast as possible.’ (MH)

The pair observe that unlike like the turtles, most species on the Barrier Reef must reproduce in the water, and that reproduction is the focus of their visit.

Diving out on the reef itself, Mike explains the structure of the reef – visible from space- is built on coral layers, expanding as the coral grow from sugars photosynthesised in the shallow water in their cultured algae cells, and by plankton snatched from the current by polyps.

These same currents that bring their food also allow the to spawn; Mike demonstrates the strength of the current by snapping a biodegradable stick of dye in front of Martha. The luminous cloud explodes out, rapidly borne on by the current. Coral reefs represent a good represent a good anchorage for corals to anchor and grow, with currents both sweeping food to them and moving on their offspring. Both Mike and Martha stop swimming against the current and they are rapidly carried right out of the frame by it.

Various shots of the reef follow, with larger fish taking shelter underneath overhangs of coral and many smaller fish darting in and out of the coral itself. Martha makes they point that living as tightly packed as this can still make it challenging to find a mate.

At the Great Barrier drop-off, with the ocean stretching out ahead, Mike spots sharks along the edge. He then discusses the various different strategies employed by sharks beyond their shared internal fertilisation, some hatching internally, some live births and some depositing egg cases and yolks.

Back on the reef, sex-changing is common between many reef fishes, like the orange Antheas. They flit about the coral in a harem protected by a singular purple male, who was once himself a smaller orange female. It’s explained that once the male dies or becomes unable to breed, a sex change is triggered in the next largest female.

We then shift to the massive scaly flanks of potato grouper, where similarly all these giants started life as smaller females before becoming male.

The grouper, clearly accustomed to being fed promptly by visiting divers, prod Mike with the expectation of food whilst Martha tickles an individual under the gills. Mike observes remoras- typically found on larger marine life- hitching a lift under some of the groupers. Symbiosis is also represented by the appearance of a cleaner wrasse, busily attending an open-mouthed grouper:

This might look suicidal, but the cleaner wrasse know it is safe as it feeds, picking off microscopic parasites and loose scales.’ (MH)

Sex changing is likewise prevalent amongst the next species highlight: a family of anemone fish tending their eggs, carefully placed on a patch behind the wafting tentacles.

Other species don’t tend their eggs at all, broadcast spawning as Mike describes it in ‘Spontaneous frenzy’ (MdG).

Some are more careful, with males clearing patches of reef in the hope of enticing a female down to deposit her eggs so they can be fertilised.

The corals we hear, produce mostly asexually, cloning themselves. The growth of the corals (remember this is before the massive bleaching events) is kept in check by nibbling parrotfish, hoping to get at the algae within. Shots show the parrotfish depositing waste as smooth sand atop the reef.

Next, we get a close up of a giant clam, the extraordinary creature jetting eggs and sperm into the water column under pressure, much to Mike and Martha’s amazement:

‘…now the molluscs are at it! …no wonder the water’s murky!’ (MH)

The fertilised eggs and larvae of countless creatures run the gauntlet of thousands of hungry mouths before they get a chance to mature. As Martha reflects:

‘Imagine going through that on your first day of nursery school!’ (MH)

Space on the reef is limited, the same being true on the outer and deeper reefs, some of which are wrecks. In a memorable shot narrated by Mike, the camera races over the surface of the water just ahead of a bow wave:

‘If, whilst navigating a boat between reefs, it hits one…’ [the camera suddenly lurches, pitching into the water] ‘….it becomes one.’ (MdG)

Next we see the outline of such a wreck emerging out of the blue as the camera approaches.

‘Very quickly the doomed vessel becomes a thriving reef community, by first attracting small, and then larger animals.’

Mike swims alongside and (incredibly) begins to pet a highly venomous sea snake.

Above the wreck immense bull rays glide under shoals of silvery bait fish. They are huge, partly from perspective, with the divers behind, but you still get the sense that they are at least a few metres across.

Snappers explore the sand for clams, then are pictured hanging under the metal struts of the wreck. Turtles rest upon the wreck before moving onwards.

Back at the reef, the camera points up towards the surface with the menacing twilight silhouette of the Crown of Thorns starfish shown. Martha and Mike come across a female broadcast spawning and Martha observes that by spawning up to 30 million eggs at a time:

‘It could be really bad news for this and the surrounding reefs.’

Mike points out that this isn’t always exclusively bad news, as it clears the surface for new growth.

Mike ‘crowns’ Martha with one of the creatures, granting her the unnerving perspective of a coral about to be consumed from the safety of her bubble helmet.

For the last sequence of the episode, Mike and Martha explain from a dusk topside that they have been waiting for an event tied to water temperature, moon, tide and time: a mass coral spawning.

Underwater at night, the pair find brain corals releasing hundreds of pre-packaged bundles of eggs and sperm like ‘polystyrene balls’ (MH) in the most peculiar ‘upside-down snow storm.’  (MH)

They explain such events are somehow sequenced, coordinated with corals of the same species hundred and sometimes thousands of miles away.

On the surface, the packets break open and mix with neighbours from the surrounding reefs. Most will be eaten, but enough will survive to keep the reef healthy, sinking back down to form new colonies.

A dizzying montage of many different species of coral spawning follows, and Mike makes the point that whilst they are immobile, their strategy works and would-be predators are overwhelmed.

Episode 5: Hawaii

In this final episode, the Sea Trek team explore the use of sound and colour by reef inhabitants before they join a team of whale researchers off the coast of Hawaii, filming under their permit to add to the natural record of the isolated islands.

The episode opens with waves smashing into shore, hissing as they turn to spray and steam once in contact with lava at the shore’s edge. At once, the island’s volcanic roots are acknowledged.

We cut to a delighted Martha and Mike who are gliding with a manta ray: ‘essentially, a huge mouth with wings.’ (MH) The creature loops balletically as it feeds.

Mike presents to camera:

‘We chose Hawaii as our final location because its isolated position right in the middle of the Pacific Ocean makes it unique: over one third of the fish living here in Hawaii are found here and nowhere else.’

After stating their aim to encounter the visiting humpbacks, they don their now- accustomed bubble helmets and dive onto the colourful reef. Here they discuss the various sounds made by the reef denizens, variously for courtship, food and communication:

‘Unfenced territories make up an invisible patchwork quilt.’ (MH)

Mike and Martha mime a pair of butterfly fish meeting each other at the edge of their respective territories. They then use a mirror to demonstrate how even a small cleaner wrasse responds immediately and aggressively to chase off his own reflection. He’s quickly joined by a surgeonfish, slashing at his own reflection in the mirror with the blade in its fin, defending against the perceived territorial incursion. Martha adds that the cleanerfish identifies itself to others through its distinct colours and jerky swimming movement.

With Martha listening aboard ship and Mike out on the reef, he directs a small hydrophone around in an arc. We hear the crackle of countless shrimp and crustaceans in the reef, then a small chirping sound. Mike moves towards the sound, hoping for damselfish, but actually sees a small moray eel poking out from branching coral.

‘It looks like you’re interviewing him’ Martha chimes in over the headset.

The little moray gapes its jaws at Mike, clearly unimpressed:

‘Do you think he feels threatened?’ prompts Martha, and Mike pulls away to resume the search for damselfish, which he finds chirping at each other a short distance away.

Back in the water, Martha tickles a sea turtle swimming overhead.

‘I could swear I see a smile on that sea turtles face!’ (MdG)

Back on the reef, small groups of yellow tangs seem to assemble, the parade along the reef getting longer and longer as more of the tangs join the school. Reaching the edge of the current, the fish broadcast spawn en masse, flinging out their offspring into the water column to be carried away.

As dusk falls, Mike remarks the ‘Reef appears rather empty’ (MdG) as resting fish slip into their hidey holes and tone down their dramatic colouration. The yellow tangs now look washed-out and the Moorish idols likewise appear drab in comparison to their daytime splendour.

At night, the pair reflect most fish appear confused by the light but a juvenile manta comes by to scoop up the plankton drawn by their torches:

‘By day they were graceful, by night we were mesmerised by their performance.’ (MH)

The scene cuts to the lava field meeting the ocean, as depicted in the opening. Filmed his time at night, Martha and Mike are silhouetted against the steam and flung spray, the glowing intense heat of the explosively cooling lava now visible in the approaching dark of evening.

Daylight and we see an overhead shot of visiting boats at anchor by Malakini, clearly an ancient volcano crater rim. Other scuba divers are pictured swimming along the reef. ‘It’s an experience that’s hard to beat’ (MH).

The pair are more speculative about the food the divers bring with them, expressing concern about how bread and frozen peas might affect the local fish population. Divers and skippers can also damage the reef by poor buoyancy or dragged anchors, but the permanent moorings at Malakini at least prevent the latter.

‘Fish sticks’ as demonstrated by Mike are put forward as a more sustainable alternative, being natural ingredients for the fish, and packaged in rice paper to avoid plastic getting onto the reef. Martha is nipped by an impatient fish. The visiting divers it is narrated, have a firsthand experience.

‘For the less intrepid, there is an alternative’ (MdG) a large passenger carrying submersible then hovers into view. Mike explains, the booming Hawaiin submarine business offers 46 tourists ‘A close-up view without getting your feet wet.’ (MdG)

Mike and Martha head to the spherical bow at the front of the submarine where sub pilot Danny sits, hovering the sub expertly above the reef.

After watching for a time, the pair take over the bucket of squid gobbets to feed the assembled fish. Chunks of thawed cephalopod flesh disappear in seconds as huge jacks shoot past their bubble helmets.

Mike is slightly reserved ‘The jacks could have taken a finger with the food’ (MdG)

Whereas Martha is more overtly critical ‘Not one of our most enjoyable encounters.’ (MH).

As the scene cuts to a busy research boat, the pair explain they have joined forces with whale researchers, operating under their permit.

Both explain that they had to learn to keep very still in the water in the hope of being approached. Around them, the song of humpbacks could be heard everywhere.

After repeated dives the whales seem more at ease with the strange duo, and are able to help the researchers identify returning individuals that have since been feeding in Alaska. Amidst the passing whales, the pair are approached underwater by a curious younger female, most likely breeding for the first time.

Sometimes the whales are gone for days, at others they seem to surface right by the boat. Martha and Mike explain that since the formal ban on jet skis and para-sailing during breeding season, the whales even come into shallow waters, meaning visitors onshore get a good view too.

In the water, the pair are approached by a young calf:

‘It seemed enormous- but it was when the mother came to the surface, we really got a sense of scale.’

The humpback pair were escorted by a guardian male, Martha explains, most likely seeking to mate with the female once fertile again.

‘They never seemed to mind us being there, on the contrary, often swimming so close we could identify their marks and scars.’ (MH)

The humpbacks were fasting throughout their time in Hawaii, there only to breed and rear their calves ahead of the return journey to their rich Alaskan feeding grounds.

Thrilled, it was at last time for Mike and Martha to return to port for the final time.

‘Then, en-route we had a totally unexpected encounter… it was unbelievable that our very last dive was with the world’s biggest fish.’

The shark seems enormous even by whale shark standards, absolutely dwarfing Mike and Martha who attempt, in traditional scuba gear, to keep pace with the giant. Peter catches stunning sweeps of the tail, as it finally leaves the divers behind and descends to the depths.

Mike narrates the closing monologue of the episode and series:

‘The most isolated land mass on earth had given us everything we could hope for and then some: from the colours and sounds of the reef to the vastness of the warm sea bathing these islands, Hawaii left an indelible memory on the entire Sea Trek crew.’

That’s it, the show is over, and for the last time we hear Roger Limb’s score (BBC Radiophonic workshop) wash over the closing credits.

The End.

Legacy of Sea Trek

So where are all my bubble-helmeted buddies rocking brightly coloured 90s neoprene? The LAMA (Laboratoire de Mecanique Applique) bubble helmets, the key selling point of the series, were eventually proved a gimmick. Production was troubled by technicalities of operating them, perhaps best noted by Mike observing they were ‘now used to the bubble helmets’ as they began their fifth and final location for diving. The dome effect would technically remove refraction, and I can only assume it took the divers some time to get used to the un-adjusted perspective not normally associated with being underwater. In addition, the need for the divers to keep the pocket of air resting on their shoulder upright clearly led to an ungainly, uncomfortable swimming position. Presenting and breathing too, was not without difficulty; without the close vacuum formed by a diver drawing breath in traditional second stage, the demand valve was attached to a solenoid, intermittently venting and replenishing air. The alternative would be a free-flowing constant delivery which would render presenting or any voice work a challenge. Any enclosed space that merged both inhalation and exhalation presented a risk of CO2 buildup and resultant risk of hypercapnia. This obviously limited the duration of the dives that could be performed, and also made equalising more challenging for the pair. I can only imagine safety divers were on high alert in spite of the shallow water, especially during Mike and Martha’s earlier dives.

To my knowledge, no productions took up use of the bubble helmets after Sea Trek, and these days where presenting is done direct to camera, it is through the use of full-face masks with inbuilt communications. The only similar experience to be found today is the similarly named ‘Sea Trek’ manufactured by the Mayfield family’s Subseasystems and aimed squarely at giving non-divers a tethered, surface-supplied underwater experience.

Beyond the technology, other aspects of the series have not aged beautifully either. Whilst not ever as obscene as Cousteau running down baby whales, mindlessly butchering sharks or deliberately blowing holes in the reef, Sea Trek does get quite handsy with its marine life. It is product of its time, being filmed in the late 1980s, with Martha and (even more so) Mike guilty of perhaps unnecessarily handling and manipulating the marine life for the camera. The dilemma comes from the balance of education versus the stress caused by contact- and I must admit a sequence like Mike’s lesson on the horn shark would have been less impactful had he simple pointed at the spines briefly before their owner swam off with them. It’s a difficult one to condone or dismiss outright, and whilst these days divers are explicitly taught not to touch, underwater presenters certainly continue to do so, even today.

Despite the above, I remain deeply touched by the series as I have explained. It formed the basis of much of my knowledge of marine systems and ecology growing up, and being a teacher by profession I do find myself pining for such documentaries that prioritise education and information over the visual spectacle emphasised in increasingly cinematic recent productions. In fact, I might argue the last wholly-underwater production to hit this balance right was another series Mike and Martha were involved with: Alastair Fothergill’s Blue Planet (2001).

Beyond Sea Trek and Blue Planet, Martha has also won a BAFTA for her Polar Wildlife Special, and lent her talents to much of the landmark wildlife programming these past forty years. Her full credits are too numerous to mention, but include the BBC’s Planet Earth (2006), Life (2009), and in her current capacity as Chief Creative Officer, Natural History and Science, at Plimsoll Productions; Night on Earth (2020), Big Beasts (2023) and A Real Bug’s Life (2024-25), the latter productions with National Geographic, Disney, Apple TV and Netflix.

Mike deGruy continued to work as an underwater cinematographer and filmmaker, working on the BBC’s The Life of Mammals, Pacific Abyss and Nature’s Microworlds with Steve Backshall to name a few. His fascination with the deep-sea environment in particular, led to his descent in the navy’s remarkable NUYT suit apparatus as part of Expedition Pacific Abyss, and prior to his tragic passing in 2012 director James Cameron employed him as a consultant on his Deepsea Challenge expedition. Mike’s passion for the ocean led to his increasing involvement in marine conservation through film. He used his personal charm and position as a respected filmmaker to raise awareness about the threats facing the oceans, particularly the impact of the Deep Water Horizon Spill in 2010. His unfinished documentary, later completed by his wife and diving partner Mimi deGruy explored the effects off the spill on the wildlife Mike grew up with and the dubious methods used to disperse the resultant pollution. Mimi’s 2019 moving documentary Diving Deep: The Life and Times of Mike deGruy thus closes the book on the extraordinary life of the ‘human exclamation mark’ and a man who has been a source of inspiration to many, not least myself.

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Thanks:

This blog has been something of a labour of love to recognise the contributions of Mike deGruy, Martha Holmes and Peter Scoones (and indeed the whole crew) to the domain of underwater photography, broadcasting and conservation. I’m lucky to have been able to extend my thanks in person to Mike and by correspondence with Martha, but obviously many others put countless hours into Sea Trek to make it a success.

These include the renowned Dutch underwater photographer Georgette Douwma, who shot almost all the stills used for domestic and international press publicity. Her photos of the sea trek expedition are worth a look at her online gallery here: https://www.naturepl.com/search?s=georgette+douwma

Lastly, thanks to my readers if by chance you managed to get to the end of this (longer than usual) entry on my blog site! I remain most grateful for your encouragement and support as my musings witter on. Jon x