Efforts to find the body of a man who jumped into the Yellowstone River earlier this week are continuing. Witnesses report that Nicholas Mostert, 20, was on the observation platform at Brink of the Lower Falls when he jumped over the railing into the river. He was then swept over the 308-foot-high Lower Falls to the bottom of the Grand Canyon of the Yellowstone. On Wednesday, searchers rapelled to the bottom of the canyon and recovered some of Mostertâs clothing from an eddy about a quarter mile downstream from the base of the falls. The park helicopter conducted another search flight Thursday morning down the length of the 20-mile-long canyon. The ground search is centered on observation points along the canyon rim with a clear view of the Yellowstone River at the bottom of the canyon, which ranges from 800 to 1,200 feet deep. The Brink of the Lower Falls is a popular observation point along the north rim of the Grand Canyon of the Yellowstone. A gauge upstream of the falls recorded nearly 6,000 cubic feet of water per second flowing into the Yellowstone River at the outlet of Yellowstone Lake at the time of the incident.