Houghton Lake is a large lake in Roscommon County. The unincorporated community of Prudenville is at the southeastern end of the lake, while the unincorporated communities of Houghton Lake and Houghton Lake Heights are on the southwest and west shores. It is the largest inland lake in the state of Michigan, and one of the largest natural inland lakes in the United States (many man-made impoundments are much larger). The lake is approximately 7 ¹⁄₂ miles (12.1 km) north to south, and about 4 ¹⁄₂ miles (7.2 km) at it widest point. Houghton Lake has c. 30 miles (48 km) of total shoreline and its waters cover 20,044 acres (81.12 km²). It is an extremely popular resort and fishing area year round. Houghton Lake is the site of Tip-Up-Town USA, a large ice fishing and winter sports festival with several events on the frozen waters of the lake itself. Houghton Lake is named after the first state geologist, Douglass Houghton who explored the area. Houghton County, in the Upper Peninsula of Michigan is also named after Douglass Houghton.