For British adventurer David Hempleman-Adams, death-defying feats have become almost routine. The scary part can be telling his wife about his plans. Which is why last month David told the missus a little white lie: that he was off on a ski trip with his buddies when in fact he planned to haul a 150-lb. sled over 300 miles of snow and sheer rock face in minus-50-degree windchill in a bid to become the first man to trek solo to the geomagnetic North Pole. "I just let him stew a bit," says wife Claire of her response after David called to fess up on April 7, the day he completed the record-setting journey. "He always sounds a bit sheepish at times like this."

And, boy, have there been plenty of them. During the past 20 years, David, 46, has become the first to complete solo hikes to both the North and South Poles, flown a hot-air balloon over the North Pole (another first) and scaled the highest peaks on all seven continents, while frequently keeping Claire, 40, and their three daughters—Alicia, 13, Camilla, 10, and Amelia, 7—in the dark concerning his designs. "What's the point in worrying them?" asks David, who views himself as a disciplined adventurer, not a reckless thrill-seeker. "I'm not so obsessed that I am going to put my life on the line."

Still, there have been some pretty close calls, including the 20-ft. plunge down a frozen waterfall that left David completing the last 60 miles of his recent journey with badly torn ligaments in his left ankle. News of the injury made Britain's Daily Telegraph—which is how his amazingly even-keeled wife first learned he was trekking to the pole. "Nothing surprises me anymore," says Claire, a lawyer who is not working while raising the children. (The family glue-making business keeps David in crampons.) "Some people just have an innate drive to do these sorts of things. I just think, 'That's one less thing he has to do now.' "