(CNN) -- Facing freezing temperatures, icy waters and encounters with polar bears, six men are attempting make history by rowing to the magnetic North Pole.
Led by British Arctic explorer Jock Wishart, and sailing in a specifically designed "ice boat," the crew must row 450 miles through dangerously ice-riddled waters before their path freezes over in September.
Five days into their voyage and speaking from a satellite phone off the coast of Devon Island, located in the Canadian Arctic Archipelago, Wishart said: "This is probably one of the most difficult exercises ever done in the polar region since (Edmund) Hillary took tractors across Antarctica. It's no light feat and it's no job for the faint-hearted."
The journey is expected to take four to five weeks and the crew will be on the water 12 to 18 hours a day, with each man rowing an average of six to nine hours, depending on conditions.
This will be ramped up in the last few days of the voyage, when the crew will need to row day and night for at least 48 hours to reach the magnetic North Pole.
In order to keep up with the physical demands, each man will consume around 5,000 calories each day. A total of 960 dehydrated meals (weighing close to 310 kg) have been packed onboard -- enough for four meals a day.
"I think the food is quite palatable," said Wishart. "But others would disagree with me. It's all dehydrated and needs water to reconstitute it. But the chili con carne goes down quite well."
With tight living quarters onboard, some of the crew have taken to camping on the barren and icy shores. But although that provides a bit more space, it presents its own set of problems.
"Last night we camped up on the beach and a couple of polar bears showed up, so we had to scare them off," said Wishart.
"There have been lots of challenges thrown at us already," he continued. "On the very first day we were moving across ice flows which were threatening to crush the boat.
"With ice, you're talking about many, many tons of weight coming down on top of you. The boat could very easily be crushed, so you have to be very careful as you navigate your way through the flows."
No stranger to a challenge, Wishart was part of the first team to walk unsupported to the Geomagnetic North Pole in 1992 and in 1998 set a new world record for his circumnavigation of the globe in a powered vessel.
Three years ago, having just completed yet another trek to the magnetic North Pole and resting in the northern Canadian outpost of Resolute Bay, Wishart took a rowing boat out onto the ice, when a friend joked, "What are you going to do next? Row to the Pole?"
"It all stemmed from that joke," says Wishart, "and four years later, here we are trying to give it a go."
The magnetic North Pole was once considered an ice-locked destination and Wishart's "Old Pulteney Row to the Pole" expedition has only become possible in the last few years due to the decreasing size of Arctic ice sheets.
"There's an awful lot more water than there used to be compared to even 10 years ago," said Wishart.
"I was up in Resolute Bay in April this year, when everything is traditionally frozen, and the strait to the south of the bay was completely open water," he continued.
So mild are conditions around the North Pole, Wishart believes this year could see the greatest melt of ice ever recorded.
"There is something happening and the mere fact you've got these mad buggers up here doing this, going where no boat has probably ever been before, shows that there is a problem up here," he said.
With an oceanographer on board, the expedition will also attempt to provide new scientific research into the Arctic's changing landscape. Measuring the salinity and temperature of the water at different depths, the data sent back will provide a baseline for future studies.
But despite the serious nature of their journey, the very real threats from ice flows and wandering polar bears, the crew is upbeat.
"There's a lot of banter going on, it's a good bunch of people, there's always a laugh and a crack, and you've got to do that because otherwise it all gets a bit miserable," said Wishart.