One reason that a Grand Canyon trip looms atop so many bucket lists is sheer length, both in mileage (277 from Lees Ferry to the Grand Wash Cliffs) and in river days (up to 27 on private winter trips). For a few paddlers, however, traversing the canyon as quickly as possible is an irresistible challenge. The Rigg brothers’ 1951 descent in a cataract-style wooden row boat was the first Grand Canyon speed run, setting the bar at just shy of 53 hours. In 2012, Harlan Taney’s sea kayak attempt (aborted after an elbow-injuring flip in Grapevine Rapid) revived the race to establish a new record. As rumors mill of another non-stop attempt this season, we highlight the canyon’s greatest benchmarks for speed.