JOHN WESLEY POWELL DESCRIBED the Gates of Lodore, on the Green River, as "a dark portal to a region of gloom" when he paddled through the 1,400-foot varnished-quartzite feature en route to the Grand Canyon in 1869. In truth, the sun shines 300 days a year on this astonishingly scenic four-day float through Dinosaur National Monument. Your daily adrenaline hit comes on Class III rapids like disaster falls and Hell's Half Mile - where the river tilts to 30 feet per mile. Stretch your legs on any of a dozen side hikes, including the five-mile round-trip up trout-rich Jones Hole Creek through a 1,200-foot-deep canyon to petroglyphs left by Fremont Indians. The rest of the time is pure chill: Pitch your tent on white sand and race western whiptail lizards down the shore.