By Josh Calhoun

April 26, 2002 Three years after summiting Everest and just six weeks since arriving by skis at the South Pole, Tom and Tina Sjögren are on the ice again, inching toward the North Pole to complete what they've dubbed the "Triple Crown" of exploration.

The Swedish husband and wife team, both 42 years old, are no strangers to exploration. In the 18 years they've been married, they've crossed jungles, sailed oceans, and climbed in the Himalayas. And the 700-mile Arctic ski is their ninth expedition in just five years.

The New York-based couple began their polar triumvirate by reaching the top of the world in May of 1999; on February 2, 2002, they completed an unsupported 1,250-mile expedition to the South Pole. Currently they are 34 days into the North Pole expedition, with only shifting Arctic ice potentially halting their quest—and Tina's bid to be the first woman to stand at all three poles.

But momentum means little when the ice is opening underfoot. According to the most recent dispatch on their expedition web site (www.thepoles.com), two nights ago a crack opened up just six feet from their tent. And pressure ridges, open leads, and most significantly, ice flow away from the pole, keep the pace so slow that some days they trudge forward merely to maintain their geographic position.

"The ice conditions are critical, even lethal right now," reports Anna Viola Hallberg, an expedition spokesperson. "The ice is cracking upwards so that some of the ice rubble is up to 15 feet high."

And since the pair opted to make the trip unsupported (no airdrops, no dogs, no engines), they must pull all their supplies in sleds behind them. That means they are skiing over huge ice mounds with 150 pounds of gear pulling them backwards—something their trainer couldn't replicate when he had them towing truck tires around an indoor beach volleyball court in New York City last year.

"Some days they wake up and wonder 'What are we doing?' But they still push on," says Hallberg. "They are a great support to each other."

They hope to reach the North Pole by May 26th so Tina can celebrate her birthday there, like she did on Mount Everest when their quest began.