One of the major rivers in Washington state is the Columbia River, which begins in Canada and snakes down through the entire state, creating much of Washington’s natural border with Oregon before flowing out to the Pacific Ocean. Other notable rivers include the Snake River and the Yakima River.
The Snake River is actually a tributary of the Columbia River and, in addition to Washington, flows through Idaho, Oregon and Wyoming. The Yakima River is also a tributary of the Colombia River, and derives its name from the tribe native to the region, the Yakama. It is the longest river that remains entirely within the boundaries of Washington state.