Castle Rocks State Park is a state park in Cassia County, Idaho, United States. The park is located in Big Cove at the base of Cache Peak in the Albion Mountains. In 2000 the Castle Rock Ranch Acquisition Act was passed, and money from the Conservation and Access funds were used to purchase the private ranch at Castle Rocks. The park was expanded by 200 acres (81 ha) in 2007. The park is located next to the Albion Division of Sawtooth National Forest and about 1.5 miles (2.4 km) from the border of City of Rocks National Reserve.