400 foot deep steep walled narrow Serpentine rock canyon cut through by the Tuolumne River and flanked by seasonal waterfalls. The 68 mile long Hetch Hetchy Railroad, that was used to construct the O'Shaughnessy Dam that submerged the Hetch Hetchy Valley of Yosemite National Park, once ran through this canyon. Now the old railroad itself is submerged under 150 feet of the New Don Pedro Reservoir.

Boating, Kayaking, Canoeing, swimming, fishing, photography, Bird watching, Bald Eagles, Ospreys,

Entire canyon is accessible by boat only year round, West Canyon rim is accessible year round via trails from the Bureau of Land Management's Red Hills Area of Critical Environmental Concern.

Fees: $7.00 / day per motorized boat, $7.00 / day per vehicle