"What really surprised us was the state of the ocean," said Lonnie Dupre, 45, a carpenter from the Midwestern state of Minnesota.

"We've seen the ocean bursting up under our feet," he said. "We expected flat, condensed ice from about 86 degrees north but when we got here the ice was completely pressured and fractured everywhere."

The 700-mile (1,126 kilometer) trek was fraught with peril as the pair pulled their canoes through blinding fog that blurred the line between the earth and sky and over ice that cracked beneath their skis and shot up out of the water.

It was the morning before they reached the Pole that they encountered their first polar bear.

A young male had followed their ski tracks, staying downwind and hiding behind drifts before circling their camp in loops.

Eric Larsen, 35, woke to the sound of his footsteps outside their red tent at about 4 am. He grabbed a flare while Dupre grabbed a video camera. The bear lumbered off slowly and seemed more curious than aggressive.

"It was like the polar bear was coming by to say thank you for what you're doing," Dupre said. "It was kind of symbolic."

Dupre and Larsen have been collecting samples of ice and snow to help scientists measure the degree to which the ice cap is retreating. Scientists are calling these measurements the Holy Grail of global warming data because no one has ever taken accurate measurements of the Arctic ice during the summer.

Satellite images are difficult to obtain during the summer months because the region is covered in fog.

"The Arctic Ocean is busting up and it's busting up quickly so we have to get on the bandwagon about global warming," he said, noting that the United States has just six percent of the world's population but creates 36 percent of the greenhouse gasses and consumes 36 percent of the world's resources.

"The Arctic Ocean could be free of ice (in summer) by 2050 which means the polar bear could be extinct."

A number of recent studies have noted how the retreating ice caps have affected polar bears, including one which found that the bears have resorted to cannibalism.

The two friends have been planning the trip for four years and were sponsored by environmental group Greenpeace which helped airlift supplies along the route. They began the trek on May 1 from Cape Discovery, off the coast of Ellesmere Island in the Canadian High Arctic.

They paddled canoes where the ice was broken into leads and pulled the canoes with skis and snow shoes where the ice was thicker.

"Physically was difficult, but mentally it was also difficult because we kept running into more and more severe conditions when we expected it to get better because the ice was so thin," said Larsen.

"We had some pretty scary situations where our lives were in danger where we were traveling across ice that was so thin it was bowing or bending underneath our skis and at one point broke away under Lonnie," he added.

Other frightening moments included white-outs where they fell down snowdrifts and times when they were traveling across chunks of ice that were moving and shooting up from the water.

Now that they have reached the Pole, Larsen said they will take a short rest and wait for satellite images to help them determine the best route home. They have not yet decided if they will make the return journey by canoe or if they will be airlifted out.

Related Links
Project Thin Ice