In a satellite telephone interview, the environmentalists said that when they arrived on Saturday, the Pole was covered with water.
"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 1,126 kilometre 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.
Eric Larsen, 35, woke to the sound of a young male’s footsteps outside their tent at about 4 am.
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," Mr Dupre said. "It was kind of symbolic."
Mr Dupre and Mr 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.
"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.
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.