Waimea Canyon–Kukui Trail, Kauai, Hawaii

The Kukui Trail in Waimea Canyon State Park is the only trail that descends into the canyon floor — a 2,000ft drop through the red and brown canyon walls that earned Waimea Canyon the title 'Grand Canyon of the Pacific.' The trail is steep and exposed in places, and the red iron-rich soil becomes extremely slippery when wet. At the canyon floor, the Waimea River runs clear and cold through pools and boulders. The contrast between the lush green windward side of Kauai and the dry red canyon on the leeward side — separated by only a few miles — is one of the island's most striking geological features.