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.' "