Harriman State Park, Public recreation area in eastern Idaho, United States.

Harriman State Park covers 11,000 acres within the Henry's Fork Caldera, three miles south of Island Park. The Henry's Fork winds eight miles through park meadows, and the shoreline in the photograph shows dark, wet stones and pebbles with clumps of dry tan grasses and reeds. A dense line of dark green coniferous trees and low forested hills rise behind the water under a cloudy sky.

Railroad investors from Union Pacific purchased this land in 1902 and operated it as a ranch and private retreat until 1977. Afterwards, the property was converted into a public park.

The park's name comes from the Harriman family, Union Pacific Railroad investors who held the land as a cattle ranch and private retreat from 1902 to 1977. Roland and W. Averell Harriman deeded it to Idaho at no cost in 1977, and the park opened to the public in 1982. Their insistence on a professional park managing service helped prompt the creation of the Idaho Department of Parks and Recreation in 1965.

The park has an extensive trail network for hiking, biking, and horseback riding in summer, while winter allows for cross-country skiing. Access is available year-round, though conditions vary by season.

Trumpeter swans wintering in Harriman State Park account for roughly two-thirds of the species' entire wintering population in the contiguous United States. The birds gather on the Henry's Fork and the park's lakes, where open water persists through the cold months.