The county has the second-highest proportion of water area of any county in the United States, behind only Keweenaw County, Michigan. Lake Leelanau is the county's largest body of inland water, formed from the Leland River dam near Leland. Glen Lake, located within the boundaries of Sleeping Bear Dunes National Lakeshore, is considered one of the most beautiful lakes in the world. A substantial portion of Sleeping Bear Dunes National Lakeshore lies within the county's borders, including North Manitou and South Manitou Islands. Leelanau has been party to substantial efforts to protect itself from growth, and to foster a nature conservancy.