Crystal Lake, the largest lake of this name in Michigan, is located near Lake Michigan in Benzie County about 25 miles (40 km) southwest of Traverse City and about 2 miles (3 km) northeast of Frankfort at . It measures approximately 2.5 by 8 miles (4 by 13 km), and has a maximum depth of 165 feet (50 m). At , it is Michigan's ninth largest inland lake. Up to and through the American Civil War years Crystal Lake was known as "Cap Lake" due to the frequent whitecaps visible on its surface. Crystal Lake is adjacent to the southern reaches of the Sleeping Bear Dunes National Lakeshore.