Goran’s first advice to us was not to push our bottom time beyond 30 minutes (by which time we’d arrive at a new definition of ‘cold’), and to stick to the maximum depth of 20m. ‘Be extra safe,’ he told us. ‘We’re a long way from help. We must look after ourselves and each other.’ He also advised us to keep our regulators in our cabins overnight and to watch out for leaks after inhaling, an early warning that our second stage was freezing up.

The first few days, en route to Antarctica, were spent watching wildlife videos, attending lectures and briefings, and scanning the waves for orcas and leopard seals. We stopped in the Falklands for a shore dive off New Island, then it was back on board to continue our journey south. We learned that much of the sea bed consists of a smooth rock-shelf with multicoloured algae sprouting in various directions. There isn’t much in the way of fish life, but there are thousands of sea stars, and brittle-stars that dance in slow motion through the algae forests. More often than not, the sea bed is covered in tiny crustaceans, to the extent that there’s no place to settle, like some over-populated seaside resort. This is very typical of Antarctic marine life: not a lot of diversity, but massive numbers of the same species, topside and underwater.

The ship’s marine biologist, Dr Nick Gales, explained that the Antarctic Ocean is unique in having a very short and simple food chain, from phytoplankton to krill to penguins to seals to whales. Where there’s krill in the Antarctic, he told us, there’s action.

An important aspect of our voyage was to make sure we minimised our environmental impact on the region. There’s a constant danger that visitors can transfer disease from one isolated colony to another, so basic rules have to be followed. Boots must be carefully washed before and after landings; no litter or human waste is to be left; and absolutely no souvenirs can be taken. Close-up encounters with wildlife do happen in the Antarctic, but they must always be on the animal’s terms.

In the following days, we settled into our diving routines, gradually acclimatising to the wind and the cold. More important, we learned the key to survival in the Antarctic, which is always to expect the unexpected. One of the Zodiac excursions was treated to an avalanche, followed by the spectacular collapse of 50m ice towers into the sea. We even found ourselves expanding our ice vocabulary, with polynyas, growlers, bergy bits, hummocks and bummocks slipping off our tongues as easily as a seal off an ice floe. Not the sort of banter you get at Swanage Pier.

The Antarctic is an utterly bewitching experience, but all the more enjoyable when sampled from the vantage of a well-heated boat, crammed to the gunwales with luxuries and scientists all too eager to provide a commentary on the strange sights. Like the crew of the Endurance [British explorer Ernest Shackleton’s ship] some 80 years before us, we played football on the ice, the difference being that we knew a speedy RIB journey would take us back to glasses of mulled wine and warm cabins.

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