It’s not easy to improve upon the hundred-mile raft trip on the Colorado River through Utah’s Cataract Canyon, the Grand Canyon’s stately upstream sister. But O.A.R.S. has managed to do it, inviting Pulitzer Prize–winning canyon expert Philip Fradkin on its trip this summer. In wooden dories, paddlers bounce through Class III rapids, spot seasonal waterfalls, and gape at the buttes and mesas of Canyonlands National Park. Side hikes reveal ruins and inscriptions from expeditions past. "I always get more out of trips when there are books or guides who give me a sense of the context of the river, and that’s what I plan to do," says Fradkin, who wrote A River No More, the definitive work on the Colorado River. After dinner, Fradkin might read from his biography of novelist and activist Wallace Stegner or chat about the history and conservation of the West’s great plumbing system.