He flies to the rescue, treks through jungles, dodges snakes, and saves rare treasures—and that's just in his private life. On-screen, such pursuits have made Harrison Ford, 65, an adventure icon. (The first Indiana Jones film in almost 20 years, The Kingdom of the Crystal Skull, just opened.)

But since 1991 the actor, pilot, and environmentalist has been moonlighting as a strategic guide for Conservation International—supporting biodiversity research, protecting endangered species, and working to persuade corporations with a history of polluting the planet to become stewards of it instead.

Ford spoke to us about high stakes, hard landings, lost worlds, and why he prefers his adventures unscripted.