An endurance swimmer hopes to highlight the effects of climate change by swimming at the North Pole.
Mr Pugh has earned the nickname "The Polar Bear"
Lewis Gordon Pugh will swim for 1km in water temperatures as low as -1.8 degrees Celsius (28.7F), the coldest waters a human has ever swum in.
The City lawyer plans to complete the swim in 20 minutes, dressed in a swimming costume, a cap and goggles.
Pugh has left London to join a Russian icebreaker which will take him and his crew to the North Pole in seven days.
He is the only person to have completed a long distance swim in all the five oceans in the world.
Pugh will attempt the record on 15 July, swimming along a crack in the ice to the geographic North Pole.
Earlier this year announcing his record attempt Pugh said: "Areas of open sea are now appearing and the sea temperature in the Arctic Ocean is predicted to increase by 9C by the end of the century.
"Just five or 10 years ago this swim would never have been possible - most people have no idea that you can find patches of open sea at the North Pole in summer.
"It's deeply regrettable that it's possible now because of the devastating effects of climate change."
During various challenges over the years, including in Arctic and Antarctic waters, Pugh has come into contact with crocodiles, sharks, hippopotami and polar bears.
His ability to endure extreme cold has also earned him the nickname of "The Polar Bear".