Redside Rapids (Mile 82. 3, Class III-IV) is a well-known rapid in Impassable Canyon featuring large named boulders (Kaiser's Helmet, Airplane Rock, Sevy's) that create a challenging gateway passage.

The rapid transforms dramatically with water levels—at high spring flows it produces massive waves and hydraulics, while at lower summer flows the sculpted granite monoliths become more visible and the navigation more technical.

The normal route runs right of center through the boulder gateway, then requires precise maneuvering to avoid midstream rocks and a large boulder on the far left.