Steamboat Rock State Park is a 3522acre 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 800ft above the lake which nearly completely surrounds it. The butte's plateau covers more than 600acre 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. Once the dams burst creating massive floods, the Columbia returned to its original course, leaving Steamboat Rock as a prominent feature of the dry Grand Coulee.