Brothers sailed the Arctic for four months

“There’s no room for error,” says Isaac Rockstrom. “The only help we have from where we are now is a couple Canadian Coast Guard icebreakers that patrol the entire Canadian Arctic.”

For the past two months, Isaac, 26, and his brother Alex, 25, have been battling the bitterly cold temperatures of the Arctic Circle.

They sailed the perilous and sometimes alien landscapes of the Northwest Passage between the Atlantic and Pacific Oceans, gathering cutting-edge data on climate change in the region.

They also encountered icebergs and strong storms around Iceland.

One of the “tricky situations”, as Isaac puts it coolly, occurred the day before he spoke to the BBC. While sailing through a fjord, he was caught in 52mph (84kph) winds blowing from a nearby mountain and was dragged ashore.

“The winds were so strong that we couldn't get anywhere with the engine on,” he recalled.

On Devon Island, the world's largest uninhabited island, there was a risk of stranding because the area was not properly marked on maps.

Alex says they had to quickly turn the other sail to get the wind in their favour and “had to take down a few things and makeshift rigging” to get the mainsail down.

But Isaac says the “hardest sea crossing of my life” was the long journey around Greenland across the Davis Strait through thick fog and ice.

He said it felt like “continuing to struggle through a storm or fog.”

“Then one day the fog cleared a little and a little tunnel appeared through the cloud cover in the distance. We could finally see Greenland for real. It was a nice confirmation that we weren't crazy.”