Hoh Rainforest is one of the largest temperate rainforests in the U.S., located on the Olympic Peninsula in western Washington state. It includes 24 miles (39 km) of low elevation forest 394 to 2,493 feet along the Hoh River. The Hoh River valley was formed thousands of years ago by glaciers.

The Olympic Peninsula is a large arm of land in western Washington that lies across Puget Sound from Seattle, and contains Olympic National Park. It is bounded on the west by the Pacific Ocean, the north by the Strait of Juan de Fuca, and the east by Hood Canal. Cape Alava, the westernmost point in the contiguous United States, and Cape Flattery, the northwesternmost point, are on the peninsula. Comprising about 3,600 square miles (9,300 km2), the Olympic Peninsula contained many of the last unexplored places in the contiguous United States. It remained largely unmapped until Arthur Dodwell and Theodore Rixon mapped most of its topography and timber resources between 1898 and 1900.