Cape St. Claire, a suburb of Annapolis, is a covenanted, unincorporated community as well as a census-designated place in Anne Arundel County, Maryland, United States. While the community of Cape St. Claire lies entirely within the CDP and accounts for approximately 80% of the homes and residents, the CDP also includes the smaller communities of Atlantis, Walnut Ridge, Green Holly, and St. Claire Court. The population of the CDP was 8,747 at the 2010 census. Contained within Cape St. Claire are three marinas, multiple parks and beaches, a shopping center, Broadneck High School, Cape St. Claire Elementary School, The Harbour School, and Cape St. Claire Swim Club.