The Whitewater River Run in Washington flows from its confluence with Ipsut Creek to the western boundary of Mount Rainier National Park. The ideal streamflow range for this run is between 800-1500 cfs. The Whitewater River is rated as Class III-IV and covers a distance of approximately 11 miles.

One of the most challenging rapids on the Whitewater River Run is known as "The Notch," which is a Class IV rapid with a narrow chute and a sharp drop. Other rapids on this run include "Pinball" and "The Elevator."

It is important to note that portions of the Whitewater River Run are only accessible during certain times of the year, as the area is within Mount Rainier National Park and is subject to seasonal closures and regulations. It is also important to follow all park regulations, including the use of proper equipment and safety gear.

In conclusion, the Whitewater River Run in Washington offers a challenging and exciting rafting experience for experienced paddlers, with Class III-IV rapids and a distance of approximately 11 miles. The ideal streamflow range is between 800-1500 cfs, and specific obstacles include "The Notch," "Pinball," and "The Elevator." Paddlers should be aware of seasonal closures and park regulations when planning their trip.