The first person to swim long distance in every ocean, Lewis Pugh, 40, has just completed his biggest challenge so far - a 1Km swim across a glacial lake on Everest at 5,300m.
Hippyshopper caught up with him at Speedo's Covent Garden store to talk about his 'extreme swims' and how he uses them to raise awareness about the dangers of climate challenge. His book, Achieving the Impossible, is out now.
How are you feeling after your challenge?
I've got a terrible sore throat. There is a lot of dust up on Everest and you can't wear a face mask while you're swimming like the climbers do.
How do you prepare for your extreme swims?
I do a huge amount of physical training, swimming in cold water, but the most important thing is to get the mind right. That's the most challenging thing because as soon as you jump in the water everything is saying to you 'get out' because it's so cold.
You have to keep on pushing. They used to talk in the SAS about the initials standing for Speed, Aggression, Surprise. When I left the SAS and went into swimming I decided that the best way to tackle cold was with speed and aggression. You have to just dive in and commit to it 100 per cent.
What influence does your time in the SAS have on what you do now?
It's huge. You really do learn how to survive in very difficult conditions and how to push boundaries and how to choose teams. The team I've just taken up Everest was 38 people. You have to choose every single one of those people really carefully.
It's not like if things go bad during the expedition you can change them. You've got to get the right people. My time in the SAS taught me how to identify the sort of people who can survive in very difficult conditions.
What was it like up on Everest?
The biggest difficulty was training for the altitude. It's a significant altitude. It's very difficult to breathe up there and all of us struggled. All of us were vomiting. As we were going up I sat in every single river to try and acclimatise my body and mind to the cold.
But I'm never swimming on Everest again. It's such a frightening place, just so difficult to breathe up there. You wake up at night and you're tossing and turning. I had very bad headaches and vomiting.
Just why did you choose to swim a glacial lake so high up on the mountain?
I chose that lake because I'm concerned about what's happening in the Himalayas. Those glaciers are beginning to retreat because of climate change and they provide water to nearly 2 billion people -one in three people in this world. There is a real risk of instability and conflict in the area unless we are able to stop climate change because we have India, Pakistan and China all relying on water from the Himalayas.
How did your love of the environment start?
Well it actually started with my father. He was at an atomic bomb test in 1952. He used to describe that moment when the bomb went off and afterwards when he had to go back to pick up all the dead animals. That left quite a mark on him. He really instilled in me the need to love and protect the environment.
Why do you just wear Speedos for your swims?
I do it for a number of reasons, but the main one is that I go round the world meeting heads of state and business leaders, trying to get them to understand what's happening, asking them to be courageous to enact laws to protect the environment.
If I'm asking them to be courageous I need to be courageous too. Also if you swam across the North Pole in a wetsuit I don't think you'd get any publicity. And these swims are about trying to raise publicity for the environment.
Can you tell us a little bit about the Polar Defence Project which you founded?
I did a swim across the north pole in 2007. Two months later the Russians sent a submarine there and planted a flag on the seabed. What they were doing is trying to claim all the rights for drilling for oil and gas all the way up to the north pole.
We've all seen what's happening now with BP's oil well in the Gulf of Mexico. I feel the Arctic should not be exploited - it should be one big national park. It's not for the countries around there to start cutting it up and drilling for oil and gas. We should be moving to renewable energy.
How long do you think it will be before the glaciers have melted completely?
I don't like to make predictions because we don't know what's going to happen. But there's a glacier just north of Mount Everest that has lost 350ft of depth in 90 years. I don't know how long it's going to take but what I've seen already really frightens me.
So what's next?
A bit of a rest. I'm moving from being a swimmer to being an environmental campaigner. I can't see me doing this for a lot longer. It's so extreme. It's really a young man's game.
I've got a couple more swims planned but not in cold water!
Thanks to Speedo.co.uk for arranging the interview with Lewis