A British man is hoping to wake up politicians in Canada and around the world to the threat of climate change by completing a kilometre-long swim in open water at the North Pole.

"I don't think anyone has ever done a swim in -1.8-degree water in a Speedo," said Lewis Gordon Pugh, who has already completed epic swims in waters from the Antarctic to the Indian Ocean.

"(But) ultimately, this is a political swim."

Pugh, speaking from northern Norway where he training in glacier-fed lakes, said he will ride up to the Pole in a Russian icebreaker.

On July 8, he will disembark with members of his team and ski around until they find the nearest stretch of open water that seems likely to stay open and is free of polar bears.

"One of the members of my team has been to the North Pole 17 times," said Pugh.

"For the last five years, he's seen open water close to the North Pole. I'm certain we'll find some."

Once he's found his swimming pool, Pugh will then strip down to his bathing trunks, cap and goggles, and dive in. The swim will be a kilometre in length, which Pugh expects to take a little over 20 minutes.

Training for the event has already involved 50 kilometre-long swims in zero-degree water. Pugh says he can stay in water that cold for 30 minutes at a time.

But the greatest challenges will be mental, not physical.

"I'm really, really focused," Pugh said.

Pugh will place the flags of 10 countries at 100-metre intervals in the snow alongside his path through the water, representing the homes of the people on his team. The fifth flag will be Canada's.

Assistants will monitor his heart rate, body temperature and stroke rate from along the ice in case his body temperature drops too quickly. The real danger, though, will come after he gets out of the water, when his heart begins to pump blood back into his frigid extremities.

That cold blood circulating back into the centre of his body is likely to keep lowering Pugh's core temperature even after he's dry and wrapped in blankets.

"When I get out of the water I'm at the most vulnerable stage," he said.

As quickly as possible, Pugh will be hustled off the ice and back on board the icebreaker for a hot shower.

"It doesn't scare me now, but when I'm (sailing to) the North Pole and crunching through ice for a whole week, I'll get a bit nervous."

The point, he said, is to shock decision-makers with the incongruity of images showing someone swimming where there should be unbroken, solid ice.

"One shouldn't be able to swim at the North Pole," Pugh said.

"This swim will be a triumph and a tragedy - a triumph that we've been able to prepare and swim at these temperatures for so long. It's a tragedy because it's only possible because of climate change."

Pugh said his message is international, but he hopes it has special impact in Canada.

"Canada is so important to me. Your government has sort of lurched away from the environment a little bit. It's a dream to try to get my message in to Canada."