Hells Canyon, Deeper Than the Grand

Hells Canyon on the Idaho-Oregon border is the deepest river gorge in North America, plunging 7,913 feet from the peaks of the Seven Devils Mountains to the Snake River below, nearly 2,000 feet deeper than the Grand Canyon. Unlike the Grand Canyon, which draws millions of tourists to its easily accessible rim, much of Hells Canyon has no road access at all and can only be reached by jet boat, whitewater raft, or multi-day backcountry trail. Its remoteness has kept it one of the most wild and untouched landscapes in the lower 48.

Source: Wikipedia