Underwater photographer Chris Riley is talking about his most insane diving experience to date. We were metres away down an icy cavern and totally oblivious to the fact that a war had broken out over our diving hole, he grins.
Two young male Weddell seals were fighting over this new territory, showering our diveline tenders in a salt ice slurry and leaving blood and fur in and around the hole. Fortunately, it was all over before we had to emerge.
His timing is impeccable. I am preparing for a plunge in the coldest, windiest, harshest and most remote continent in the world, with an environment so hostile that dives are unpredictable and equipment malfunctions common.
I am unlikely, however, to encounter warring seals. My dive is far away from sea ice, on a relatively small iceberg that rises 8m from the waters surface.
The dive is part of an underwater filming expedition organised by the Japanese broadcasting company NHK. We had voyaged from Hobart, Australia, across the Roaring Forties, through the Furious Fifties and finally into the Screaming Sixties, to film as much marine animal action as we could in a month.

Down below, the first thing that hits you is the numbing purity of the water. It is mid-December, and the visibility has just started to turn. From the surface you can make out the soft orange glow of kelp 40m below. Yet the members of the dive team are disappointed. They have seen better.
In early spring (October to November), there is no algae to taint the particles of water. Thats when visibility can reach for miles.
Jeannie Ackley, a contributor to the classic Antarctic TV documentary Life in the Freezer, had dived under the Ross Sea Ice Shelf on a previous expedition. We could see the light shining through from an ice runway at Cape Armitage, half a mile away. It was crystal-clear, she recalls.

Chris Riley waxes lyrical after filming in the Ross Sea: We were hanging at 30m. Below us the bottom was 1500m and inky black. Like a spaceship the ROV cruised out from beneath the rounded, planet-like ice flutes of the Erebus Glacier Tongue, 300m below.
East of us, sunshine was shafting down a tide-crack one mile away, and the tiny specks we could see rising into the shaft were Weddell seals using the crack for a breathing hole.
Riley remembers the experience as a total visual and sensory overload - he calls it his inner-space walk.
According to Paul Goldsworthy, a researcher who has completed more than 200 dives for the Australian Antarctic Division, visibility can change dramatically towards the end of summer. At the start of the season, the water clarity is exceptional, but by mid-January the plankton has bloomed and visibility can be as low as 2m, so we often need assistance to relocate the dive-hole or dive-boat, he explains.
For my dive, 40m is more than enough. I can see our small iceberg dropping away to a living bottom, silver ice cod perched in its electric-blue crevices.
We follow the pockmarked wall down to the icebergs anchorage point. It has stuck fast and I am relieved. Jeannie Ackley had told me how she had just reached the bottom to shoot an icebergs grinding point when everything turned pear-shaped.
I was looking through the viewfinder trying to focus and the berg looked really weird - then I realised it was rolling, so I just started finning backwards. She made it to the surface with the film intact as the iceberg, 15m deep and 2m above water, continued to roll away from the divers.

To dive an iceberg is to dive what appears to be a living, breathing entity. Bizarre currents can form along its edge and you find yourself suddenly sucked up or down several metres, propelled by an unseen force.
Drifting up towards the atmosphere are tiny bubbles of ancient air, trapped when the water first froze. The silvery globules stick to the camera lens and play constant havoc with its focus.
This berg has fixed itself firmly to the substrate, rocks embedded deep inside its base. The surrounding kelp is a mixture of rich maroons, golden yellows, bright green flushes and starfish pinks. People who state that the Antarctic has few colours have never dived here.
Above these rich fields, we see the strange form of the sea-butterfly, a free-swimming pterapod. Many of the marine invertebrates appear to be on steroids. We find nudibranchs the size of a mans fist and sponges that span several metres. Gigantism is a feature of some of Antarcticas sea creatures.
Twenty minutes into the dive, however, my fingers are screaming with pain and I make my way back up. My wetsuit gloves, though thick and many-layered, are no match for -1.8°C waters, and my fingertips are swollen and as useful as lumps of wood, and remain sensitive for days afterwards. Dry gloves (as I found out the hard way) are the preferred choice.
Full-face masks are warmer but in free-flow situations it is far easier to swap regulators while wearing a normal face mask. Special full-faced neoprene hoods can be used, while Vaseline smeared over bare facial skin helps.
Underwater camera-operator Brady Doak remembers one expedition on which a team member failed to take adequate precautions:
One diver had been down more than an hour. He returned with a bright red face which looked sunburnt, and days later the skin began to peel off.

High-flow regulators with sealed first stages are prerequisites, though the first stage often returns to the surface looking like a giant ice-cube. The greatest problem, however, is caused by a divers breath. Droplets of condensation can slowly build up and freeze inside the second stage, causing the regulator to free-flow.
I encounter this on every dive, which is why we all have two tanks and two independent sets of regulators, complete with computer and separate air and depth gauge.
We also have a safety diver with several surface attendants and a dive supervisor, kitted-up ready to go at any moment. But the above-water environment is generally harsher than under water, and the people here are left exposed to the changing conditions.
Its often much more comfortable being the diver than being the surface attendants, standing on the ice in the chilling wind with wet hands and icy feet! says Paul Goldsworthy.
Perhaps one of the biggest causes for concern are the Katabatics, gravity-driven winds that rush down from the polar plateaus towards the sea. These can quickly reach 70 knots-plus and add a terrifying windchill to the already freezing environment. Blizzard-like conditions will easily cancel a diving day.

Our expedition has a recompression unit onboard, but tourist vessels often do not have this luxury. For Goldsworthy this is a concern: Diving in Antarctica includes several known precursors for DCI, such as cold water, anxiety, dehydration and unfamiliar gear. Without a recompression chamber on board each vessel, theres a long trip back to the nearest port for treatment.
To minimise the risk, tourist vessels offering diving try to avoid areas with high concentrations of ice, preferring icebergs and small ice floes, but even small icebergs are not always safe.
So why would any sane recreational diver seek to dive in such an inhospitable environment Well, in a landscape so void of life above water, the underwater contrast is huge.
The foreign squeals, rumbles and whistles of a Weddell seal; the spiralling trail of bubbles left by a penguin; the colours and shapes of icy underwater grottos and stalactites; the diversity and rich colours of fields of kelp; the benthic assortment of sponges, seastars, amphipods and soft corals - it all adds up to an unforgettable experience.
Theres a thriving community underwater, says Brad Doak. Everything works in slow motion, though - its not busy like a tropical reef.

Ultimately there are many factors that will decide whether you will experience the southernmost seas on the planet. Among them are your level of diving experience, ice and weather conditions, opportunity and money, but for those who are passionate about their sport, its like visiting another world.


An old blue-green iceberg.

A dive tender retrieves divers from among pack ice


Jeannie Ackley and diveline tender Ed Mickelson at a Weddell seal hole in pushed-up sea-ice

ROV and Weddell seal at the Mount Erebus glacier tongue - Weddells use their teeth to keep the ice open

Diving an iceberg at Cape Evans

diver with giant cup sponges at 27m under 2m-thick fast ice at Cape Evans, Ross island, near Scott Base