[8] Mount Rainier is the source of nine major rivers and their tributaries: the Nisqually, Puyallup, Mowich, Carbon, West Fork White, Huckleberry, White, Ohanapecosh, and Muddy Fork rivers.

It flows southeast through Indian Bar, a broad, flat area of rocky debris.

The river splits into two channels which join at the south end of Cedar Flats.

The Grove of the Patriarchs trail crosses the river and loops through the island created by the Ohanapecosh's channels.

Just downstream from the rejoining of the two channels the Ohanapecosh flows by the east end of Stevens Canyon Road, which joins State Route 123 near the river.

The high ridge west of the Ohanapecosh River north of the Stevens Canyon entrance road is called the Cowlitz Divide.

Both form a continuous ridgeline separating the watershed of the Ohanapecosh from the Muddy Fork Cowlitz River.

This southeastern part of Mount Rainier National Park is known as the Ohanapecosh area.