Happily, the boats are also extraordinarily maneuverable, which may explain why pioneering river rat Martin Litton still paddles one. Even better: A trip on a dory is the slowest and longest of Grand Canyon river journeys, 15 to 18 days. That means time to debark and hike to places like Vasey’s Paradise, a ferny oasis where a waterfall tumbles into the canyon; rest in solitude inside Red Wall Cavern; climb to Anasazi granaries 457 meters above the river