AS WE HEADED AWAY from the rickety pier on a calm, sunny day we felt ludicrously over-dressed in our drysuits. Carlos, a big man with an infectious, high-pitched laugh, owns the dive centre and was our guide and skipper on this trip.
Ushuaia is a beautiful natural harbour, C-shaped, sheltered from the prevailing wind, framed by forested mountains losing their dusting of snow as spring kicks in.
Carlos knows that I adore sea-lions, and on the way to the first dive he took us to see the colony. The marine police don’t allow diving or snorkelling near the rookery, but they are a big draw to boat-loads of visitors. It’s breeding season, and like all sea-lions the massive, bloated beachmasters who had already secured harems dozed lightly, saving their energy for fighting and fornication over the next few weeks.
Ushuaia is an isolated small town at “the end of the world”, as the local tourist industry is far too fond of calling it. Ushuaia is nestled at the edge of the Beagle Channel, where the Andes mountains finally drop into the sea at Tierra del Fuego, the toe of South America. It is also where almost everyone who visits Antarctica departs.
It’s a scruffy little frontier town in a gorgeous setting. Each house seems to have been built by an individual, with a complete and refreshing lack of regard for the design of his neighbour, or to the self-perpetuating bureaucratic whims of town-planners.
The Beagle Channel, the protected passage through the tip of South America to the Pacific, offered an alternative to the horrifically dangerous rounding of Cape Horn.
It was surveyed and charted in the late 1820s and early 1830s by a brilliant young sea captain who went on to invent weather-forecasting.
His name was Robert Fitzroy, and the naturalist travelling with him, 22-year-old Charles Darwin, was as impressed by the wildness of the place and the sheer density of marine life as visitors are today. It’s a shame that he never got to see beneath the surface.
The channel is still unspoilt, wild and beautiful, very much as they found it in the early 19th century. It’s rugged and green and wild both above and below the surface.
Leaving the sea-lions to the tourists, Carlos took us past the first island into the middle of the channel, and our dive-site, H-island.
Plunging into the 7° water provided an abrupt reminder of why we had the drysuits on. Quickly we slipped from bright sunlight into green gloom.

THE VISIBILITY WAS FAIRLY POOR, and our companions, new to drysuit-diving, landed heavily. For a couple of minutes the algae and detritus on the bottom was pretty much all we could see.
Most diving is near dense forests of Macrocystis – giant kelp. It’s not at all like California’s giant kelp. It’s shorter, more tangled and more closed-in.
Beneath the shadowy canopy of enormous fronds it feels like being in a labyrinth made of masses of ropes loosely twisted out of rubber tubing.
Visibility is poor in spring and summer because of rich phytoplankton – the water is usually green-brown and almost peaty or soupy.
Only a handful of places on Earth have such thick, productive waters. The downside is visibility, the upside an abundance of marine life.
It’s an alien world, and if you choose to head right into the undergrowth it can get dark, grab and close in on you.
We find ourselves tucking our shoulders in, twisting slowly, breathing in and out to thread our way over and under and around and through the undergrowth.
It’s best to move fluidly and slowly, and it can take a while to realise that you have snagged an elastic stem as thick as your little finger and are slowly stretching it out over several metres. It has a surreal, dark and heavy “haunted forest” beauty.
This is the closest I’ve ever been to experiencing claustrophobia. It doesn’t feel genuinely dangerous, however – I’ve always found it easy to extricate myself from the minor tangles that result from swimming right into the densest kelp.
I enjoy poking around in the tangled mass for the sheer joy of the weirdness of this world, but also to seek critters.
The holdfasts, the kelp’s beer-keg-sized mass of root-like anchors, often writhe with brittlestars and seem to be a haven for all manner of small beasts.
The beds of algae host entire communities, and the canopy above yet more. Tiny violet snails, limpets and urchins are everywhere, and there is a surprising range of nudibranchs, as well as gorgeous painted shrimps and an array of starfish.
You don’t have to weave into the thickest kelp, because most marine-life action is far more accessible around the edges and on the rocky slopes.
The Beagle seems to specialise in crustaceans, from the enormous centollas, the thick-legged red king crabs up to a metre across beloved of Ushuaias restaurants, to a whole host of decorator crabs and hermit crabs.
My favourites are two related spider crabs. One is a ghoul-faced, tarantula-like hairy-legged crab that seems to slump in lethargy and get overgrown with foliage. The other is its strutting cousin, which stands erect, sticks its chest and chin out at you and raise its legs in a threat bluff.
There is one little crab that stands apart even in this menagerie, dominating the Beagle Channel in a spectacular way. In the UK we are familiar with five species of squat lobsters that are a regular part of our diving. They’re not particularly squat, and they’re not lobsters.
Down here, members of the same genus as one of our squatties, Munida, are much, much more abundant. Here they are called bogavantes in Spanish or Munid shrimps in English, but they’re not shrimps, either.
In the UK they are common, but the waters here have more food, and they carpet the sea floor, making up half of the considerable animal biomass of the entire Beagle Channel.
They feed the sea-lions, the local penguins and almost everything else. Every bit of ground or kelp seems to be alive with them, and they’ll even use one of their larger cousins as a temporary perch (see lead photo).

THE KELP FRONDS SOMETIMES appear to be coated with them, and on a descent the gravelly sand bottoms come alive with thousands of them, darting away with a couple of rapid twitches of their lobster-like tails, followed by a smooth glide.
They don’t walk like crabs and they don’t swim like shrimp. They shoot backwards with their arms trailing in front, looking rather like tiny fleeing octopuses.
When they’re young, they swarm through the water column in the late summer, and early explorers knew of the unbelievably thick swarms by my favourite of their names, lobster-krill.
At the end of their first summer, they get heavier and settle to feed on the dense, nutrient-rich detritus on the sea floor. Here is where you find them on the Beagle Channel dives.
What we see here, however, is only a tiny remnant of the population. Most lobster-krill never make it to adulthood. Like true krill, the youngsters provide an enormous food resource for the huge numbers of squid, fish and marine mammals living around the Patagonian Shelf.
The name lobster-krill is incorrect, too. The youngsters do live a somewhat krill-like existence, but they are never the sleek, open-ocean marathon-swimming spindles that true krill are.
To give them their true name you’d have to call them Galatheid crabs, which just seems a bit naff. They are more closely related to hermit crabs, porcelain crabs or king crabs than anything else. So I’ll stick with lobster-krill.