The United States Virgin Islands are a group of several dozen islands and cays located in the Caribbean, about southeast of Florida, north of Venezuela, east of Puerto Rico, and immediately west and south of the British Virgin Islands. The U.S. Virgin Islands lie near the boundary of the North American Plate and the Caribbean Plate, roughly south of the Puerto Rico Trench and near the Anegada Passage, a key shipping lane. Together with the British Virgin Islands, Vieques, and Culebra, they make up the Virgin Islands archipelago. The hilly, volcanic islands of Saint Thomas () and Saint John () border the North Atlantic Ocean to the north and the Caribbean Sea to the south. The larger island of Saint Croix () lies to the south across the Virgin Islands Trough and is entirely in the Caribbean Sea. Charlotte Amalie, Saint Thomas is one of the best natural, deepwater harbors in the Caribbean. The Islands have many well-known beaches, including Magens Bay (Saint Thomas) and Trunk Bay (Saint John), and coral reefs, including the Virgin Islands Coral Reef National Monument and the Buck Island Reef National Monument. More than half of Saint John and nearly all of Hassel Island are owned by the U.S. National Park Service. Statistics Geographic coordinates (capital Charlotte Amalie): Islands: Saint Croix, Saint Thomas, Saint John, Water Island, many other islands Area: total: 738 sq mi (1,910 km²) land: 134 sq mi (346 km²) water: 604 sq mi (1,564 km²) Comparative area: twice the size of the District of Columbia Maritime claims: exclusive economic zone: territorial sea: Land use: arable land: 5.71% permanent crops: 2.86% other: 91.43% (2005) Irrigated land: 1 km² Natural hazards:frequent and severe droughts and floods; occasional earthquakes; rare tsunamis Environment—current issues: lack of natural freshwater resources Terrain The islands' terrain is mostly hilly to rugged and mountainous with little level land. Crown Mountain, on Saint Thomas, is the highest point in the U.S. Virgin Islands at 1,555 ft (474 m). Sea level is the lowest point. It has a coastline of . The territory is known for its beaches and plentiful sunshine. Climate The U.S. Virgin Islands enjoy a tropical climate, moderated by easterly trade winds and with relatively low humidity. Temperatures vary little throughout the year. In the capital, Charlotte Amalie, typical daily maximum temperatures are around in the summer and in the winter. Typical daily minimum temperatures are around in