Steamboat Rock State Park is a 3,522-acre (1,425 ha) Washington state park located near the north end of Banks Lake in the Grand Coulee. The park takes its name from the landscape's dominating feature, Steamboat Rock, a basalt butte that rises 800 feet (240 m) above the lake which nearly completely surrounds it. The butte's plateau covers more than 600 acres (240 ha) and was used by nomadic Native American tribes and by early settlers. During the last Ice Age, the monolith stood as an island in the new bed of the Columbia River where it had been diverted by ice dams.