Diving into freezing water to test their immersion suits and dragging tractor tyres through the mud in Dartmoor are just some of the punishing tasks a team of explorers have put their bodies through in preparation for an assault on the North Pole.

The Catlin Arctic Survey team, led by Pen Hadow, will depart for the Arctic in February for a groundbreaking three-month trek to measure the remaining thickness of the sea ice.

The data gathered by the team, which also includes photographer Martin Hartley and polar explorer Ann Daniels, will form pivotal evidence to be presented to the United Nations Climate Change Conference in November.

The team are currently in Broughton Island, Canada, making the final preparations for the trip and embarked on a four-day mini mission on January 15 to test their radar equipment which will take more than 10 million measurements over the course of the main expedition.

Pen said: “Conditions are tough. Broughton Island is currently in darkness for at least 20 hours per day.

“You can't see your hand in front of your face, and if your overhead torch goes out, that is it.”

The team has completed a rigourous training routine in Dartmoor under the guidance of former Royal Marine Jon Stratford. It has seen them camping out on the moors and trekking with rucksacks full of rocks to ensure they are physically and mentally prepared for the trip.

A cold chamber at the Royal Navy’s Institute of Naval Medicine in Portsmouth provided the team with a valuable opportunity to experience the freezing Arctic temperatures and they have been training in temperatures reaching -30C.

Back in Canada the team are practising their daily routine so it becomes second nature before the trip and, as the 750-mile route will involve swimming through areas of sea where the ice has already melted, the team are taking lessons from Inuit clam-diver Stevie Audlakiak in how to survive in the icy water.

Pen said: “It's vital we make sure we have tested everything in the extreme conditions of the Arctic winter.

"We also need to be sure we work well as a team, so our daily routines for trekking, eating, science work and so forth have to be practised so we are in the best possible shape when we cross the starting line in late February.

“After years of preparation, that will be our moment of truth."