Most of the river flows within Yosemite National Park in the Sierra Nevada of California.

This canyon comes to an end at a large bowl-shaped valley where the river passes the north side of Wawona and receives Chilnualna Creek from the right.

After passing under Wawona Road (the south entrance road to the national park) the river drops into another broader, deeper gorge running north, receiving Alder, Rail, Big, and Bishop Creeks, all from the right.

Soon the river turns west, crossing the boundary of Yosemite National Park and the Sierra National Forest and entering the foothills of the Sierra Nevada, and merges with the Merced River some 25 miles (40 km) downstream of the end of Yosemite Valley.

[3][4][5][6] The river was mislabelled "Illilouette Creek" on 1871 California Geological Survey reports.