"A journey must meet two criteria to be worth all the time, effort, and risk," explains Irish explorer Tim Severin. "One: It must be original. Two: It must stand a reasonable chance of advancing the knowledge of mankind." And if these criteria define the difference between an explorer and a mere adventurer, then Tim Severin is the Magellan of our time. His 12 expeditions include sailing a hand-built medieval vessel from Oman to China in 1980-'81 to examine the tales of Sinbad the Sailor, skippering a tiny leather boat from Ireland to North America in 1976 in an attempt to prove that 6th-century Irish monks had the technology to discover the New World, and, last year, sailing among the fly-speck islands off Central America seeking the location that inspired the Robinson Crusoe fable. So what's next? "I prefer to do it first," says Severin, 61, "then talk about it." Mark Jenkins
Open a World of Adventure
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