Castle Rocks State Park, State park in Cassia County, Idaho, United States.

Castle Rocks State Park is a nature reserve near Cache Peak featuring distinctive granite rock formations and pinyon pine forests throughout its grounds. The terrain offers varied landscape with craggy outcrops and wooded areas suitable for hiking and rock climbing.

The land became an official protected area in 2003 when transferred from the National Park Service to Idaho's state parks department. This transition marked the start of managed conservation efforts for the site's natural features.

The park lies in Big Cove, a corridor between the Albion Mountains and the City of Rocks National Reserve, and its name comes from the granite outcrops that resemble a castle. The ranch land here was privately held until the Castle Rock Ranch Acquisition Act of 2000; Idaho took over management on May 25, 2003.

Castle Rocks State Park lies in Big Cove at the base of Cache Peak, about 1.5 miles (2.4 km) from City of Rocks National Reserve and next to the Albion Division of Sawtooth National Forest. Idaho Parks and Recreation has managed facilities and recreation here since May 25, 2003. The park covers 1,692 acres (685 ha), expanded by 200 acres in 2007.

The site hosts hundreds of rock climbing routes nestled within one of Idaho's largest pinyon pine forest stands. This combination of climbing opportunities and the uncommon forest type makes it a notable destination for both climbers and nature enthusiasts.