Of all the creatures in the world that really frighten me - the hyena in Africa, the great white shark - leopard seals are near the top of the list. They're killers. If my team spots one, they'll pull me out of the water.

On my second swim at Deception Island, the water was very clear and I was looking at hundreds of whale bones beneath me. It was a graveyard from the whaling some time in the 1920s-30s.

Not to be too grandiose about it, but in a way I see myself like Sir Edmund Hillary. The water was my Everest.

There's nothing in the sea this fish would fear. Other fish run from bigger things. That's their instinct. But this fish doesn't run from anything. He doesn't fear.

In the cold, all the blood rushes to your core to protect your heart, lungs, kidneys, liver, and brain. When you leave the water, the blood rushes back to your arms and legs, absorbs that freezing cold, and brings it back to the heart.

Britain has bred many great explorers, but they seem to get so little coverage compared to soccer and rugby players.