Between Hood River and Mosier, the five mile Twin Tunnels segment passes through two climate zones. Starting at the east Mark O. Hatfield Trailhead near Mosier, the trail leads through semiarid terrain dotted with Ponderosa pine for about a mile until you reach the Twin Tunnels. Spectacular geologic formations tell the story of the gorge's creation.
After passing through the tunnels, you'll emerge into a forest of fir trees and other common western Oregon plants. Viewpoints along the 3.5 mile segment from the tunnels to the west Mark O. Hatfield Trailhead overlook the river.
To reach the Twin Tunnels segment from the west, take Exit 64 off I-84 and follow the signs. To reach the Tooth Rock segment from the east, park under the Bridge of the Gods in Cascade Locks.
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