The Whitewater River, located in the Olympic National Park of Washington, is a popular destination for kayakers and rafters due to its challenging class IV-V rapids. The ideal streamflow range for the Whitewater River is between 500-1500 cubic feet per second (cfs), which typically occurs in the spring and early summer months.

The river is broken up into three segments, with the upper segment being the most challenging and technical. The upper segment spans 6.5 miles and is rated as a class V+ run, with several steep drops, waterfalls, and tight boulder gardens. The middle segment spans 4 miles and is rated as a class IV-V run, with continuous rapids and several large drops. The lower segment spans 2.5 miles and is rated as a class III-IV run, with fun, playful rapids and a few technical sections.

There are several notable rapids on the Whitewater River, including "Entrance Exam," "S-Turn," "Corkscrew," and "The Slot." Obstacles such as strainers and log jams can be found throughout the river and should be navigated with caution.

Regulations for the Whitewater River include obtaining a permit from the Olympic National Park, using Leave No Trace principles, and following all safety guidelines and regulations set by the National Park Service. It is recommended that paddlers have advanced whitewater skills and experience before attempting the Whitewater River.