I’M ON A BOAT WITH A TV crew close to the craggy coast of Sark, one of the smallest Channel Islands, 80 miles south of the British mainland.
With one of the largest tidal ranges in the world, dives here have to be planned meticulously. Some of the best sites have only around 20 minutes of slack water.
Add to this the complications of filming and recording sound under water, and you have an operation that requires military precision.
The dive team and I are fully kitted up, the detailed briefing has been delivered and the underwater camera is ready to roll, but we’re early, so now it’s simply a case of waiting for the tide to slacken.
I look up at the granite cliffs and can just make out the footpath that zigzags down to the highest entrance to the Gouliot Cave system, the route I took six years ago when I was filming for the BBC series Coast.
My guide then was septuagenarian Dr Ann Allen, a regular visitor to Sark with a passion for the island’s flora and fauna, and the expedition was timed to coincide with one of the lowest tides of the year.
After a scramble down a section called the Chimney, a squeeze though the Slits and a knee-deep wade through the dark Sponge Cave, Ann led the way to the Jewel Cave. The walls of the cave were encrusted with anemones, sponges, soft corals and all sorts of other marine life uncovered by the exceptionally low tide.
Most amazing were the beadlet anemones, which covered the walls like thousands of giant fruit gums. A shaft of light streamed in from above, and ahead of us a flooded gully led intriguingly around a corner, but the tide never falls far enough to explore further on foot.
As wonderful as the sight was, I couldn’t help but wonder what the Jewel Cave would look like under water when all the marine life was back in its element, and it was then that I promised myself that one day I would dive there.

SO HERE I AM, six years later all ready to experience this magical place from beneath the surface.
The skipper gives us the go-ahead and we jump in, heading against a slight current towards what looks like a solid wall of granite. Just beneath the surface there’s a triangular cave dropping down to a pebbly seabed dappled with light just 5m below.
The camera pair fin in ahead of me, and I follow as the cave narrows and grows darker. In the light of my torch I pick out patches of vivid orange, yellow and green – the sponges that give this section of the caves its name.
There are also the fluffy white digits of dead men’s fingers, their delicate white tentacles wafting in the surge.
About 12m in, the cave roof dips and the pebbles have been banked up, leaving what appears to be an impossibly small passage through which to swim.

THE SURGE, amplified by the narrow space, pulls me closer, and I can feel as well as hear the “wumph” as it reverberates through the cave.
Staying low to the pebbles, I time my swim with the surge and am sucked through the gap, which fortunately is larger than it looked from a distance.
To my left, a greeny-blue glow indicates another opening to the sea, my way in when I explored the caves on foot. I follow the lights of the other divers to the right along a dark passageway about 3m wide.
The walls are dotted now with beadlet anemones, and then in an alcove to my left there’s a beautiful swathe of plumose anemones. Last time I saw these they were a gelatinous sprawl collapsed on the rock, totally unrecognisable as the statuesque, peach-coloured beauties with hundreds of delicate tentacles I see now.
Ahead, a column of rock divides the passage in two and light beckons from either side. The surge is strong again here, and swimming is a case of two kicks forward, one kick back, before I’m “wooshed” into the Jewel Cave itself.
The walls here are liberally carpeted with marine life, much of it spot-lit by shafts of turquoise from above. There are more huge patches of green, yellow and orange encrusting sponges, and some of the largest barnacles I’ve ever seen.
Lower down there are elegant and jewel anemones in every shade of pink, purple, green, orange and white, both species normally found in much deeper water well below the low tide-line.
Some areas are covered in pale yellow stems of oaten-pipe hydroids, each topped with a delicate pink, flower-like polyp.

THE STARS OF THE SHOW, however, are the thousands upon thousands of beadlet anemones. Last time I saw them they were closed up and hunkered down, but now they are blossoming with their tentacles fully unfurled.
As well as the common red form there are beadlets here with the rarer orange and green colourings. As the surge wafts their tentacles backwards and forwards the vivid blue “beads” of the poison sacs that give them their name are revealed.
These are brought into play in the battles over territory waged by these anemones, each one fighting for a prime position on the wall.
The water in this section of the caves is just 4m deep, and when I drift up to the surface I see thousands more beadlet anemones clinging to walls for several more metres above. It’s easy to see why this is called the Jewel Cave!
Like all the marine life here, the anemones thrive on the blizzard of plankton that is swept by on the current that surges through the caves every day, pausing only to change direction.
On neap tides, there’s around 20 minutes of slack water before the tide turns, which is what we have today, but on springs there are just a few minutes of stillness before it pours through the caves the other way.
As well as the plankton-feeders there are those that feed on them, such as nudibranchs, cowries and painted topshells. Crabs, shannies and tompot blennies peer from cracks in the walls, and I’m told that this is also a good place to see topknots and sea scorpions nestling among the anemones.

MY TIME IN THE GOULIOT CAVES is rapidly coming to an end. The tide has turned and, just as predicted, we’re being pulled down a gully towards the open sea.
The walls of beadlet anemones give way to a carpet of hydroids mingled with jewel anemones, soft coral and bulbous yellow mounds of boring sponge.
As we’re swept out of the exit of the caves, we surprise a shoal of mullet feeding above a swirling forest of seaweeds in Harve Gosselin, the bay on the other side of the headland where our dive-boat is waiting to pick us up.
Our computers read barely 5m, and we’ve travelled only about 150m, but my dive through the Gouliot Caves was worth waiting six years for.
The caves aren’t the only underwater treats on offer around Sark. The island is surrounded by islets and reefs that offer some spectacular diving, and because of Sark’s southerly position there’s a slightly exotic air to its blend of marine life.
L’Étac, an islet to the south, has sheer rock walls, gullies and boulder slopes dropping down to more than 40m, and is home to the fabulous sunset cup coral, one of the rarest corals in the British Isles.
Like the nearby submerged reef of the Vingt Clos, once you drop beneath the kelp the walls are swathed in jewel anemones, red fingers of soft coral and pink sea fans.
The reefs of Pavlaison and Grune du Nord to the east of Sark and Guillaumesse and Les Dents to the west are less sheer but just as colourful. Southerly species to look out for include the black-face blenny, soapy starfish and gorgeous anemone prawn, a purple-striped beauty that lives beneath the tentacles of the snakelocks anemone.
In the shallows, if you peer into cracks in the rock or beneath boulders you may be lucky enough to spot a real Channel Island speciality – the ormer, an abalone-like mollusc prized as a local delicacy.

OTHER MORE FAMILIAR SPECIES likely to be encountered are lobsters, common urchins, conger eels and spiny starfish.
Crawfish and anglerfish are seen occasionally, but cuckoo wrasse are pretty much guaranteed to appear on every reef dive around Sark. They live in groups with a harem of females and a single male.
As budding marine biologists know, all cuckoo wrasse are born female, and should anything happen to the male the oldest female in the group changes sex internally. Her peach colours transform into dazzling blues and oranges as she becomes a he.
Both sexes are territorial and inquisitive, swimming right up to divers and watching their every move. They seem to react to their own reflections in masks and camera ports, which may explain why they sometimes take a nibble at a diver.
The wealth of marine life and good vis attracts underwater photographers and marine biologists to Sark and, of course, there is the island itself to explore.
With no cars allowed, however, you need to pace yourself. The Harbour Hill transport, known locally as the Toast Rack, meets only the scheduled ferries, and the walk up the hill is quite a strenuous one.
Once on top you can explore by foot or bicycle but if you’re out after dark, be prepared. There’s no street lighting, so the view of the night sky is stunning on a cloudless night, but when there’s no moon you definitely need a torch!

GETTING THERE:The Isle of Sark Shipping Co runs from nearby Guernsey throughout the year (www.sarkshippingcompany.com) and there are also sailings from Jersey and France with Manche Iles Express in summer. Condor Ferries (www.condorferries.co.uk) runs a fast ferry service from Poole and Weymouth to Guernsey and several airlines fly from around the UK to Guernsey.
DIVING: Sark Diving Services runs weekly dive trips for experienced divers, www.sark.ci.com. Wreck and Reef Charters runs day and weekend dive trips to Sark from its base in Jersey, www.wreckandreefcharters.com MONEY: Guernsey, Jersey or UK pound.