Hosmer Lake is a natural body of water in the central Cascade Range in the U.S. state of Oregon. Nearly 5,000 feet above sea level, the lake is part of a volcanic landscape about 20 miles west-southwest of Bend along the Cascade Lakes Scenic Byway. In 1962, the United States Board on Geographic Names changed the name from Mud Lake to Hosmer La…Hosmer Lake is a natural body of water in the central Cascade Range in the U.S. state of Oregon. Nearly 5,000 feet above sea level, the lake is part of a volcanic landscape about 20 miles west-southwest of Bend along the Cascade Lakes Scenic Byway. In 1962, the United States Board on Geographic Names changed the name from Mud Lake to Hosmer Lake in honor of Paul Hosmer, a naturalist from Bend.