The territory consists of four main islands: Saint Thomas, Saint John, Saint Croix, and Water Island, as well as several dozen smaller islands. The main islands have nicknames often used by locals: "Twin City" (St. Croix), "Rock City" (St. Thomas) and "Love City" (St. John). The combined land area of the islands is roughly twice the size of Washington, D.C.
The U.S. Virgin Islands are known for their white sand beaches, including Magens Bay and Trunk Bay, and strategic harbors, including Charlotte Amalie and Christiansted. Most of the islands, including Saint Thomas, are volcanic in origin and hilly. The highest point is Crown Mountain, Saint Thomas (1,555 ft/474 m). Saint Croix, the largest of the U.S. Virgin Islands, lies to the south and has a flatter terrain. The National Park Service owns more than half of Saint John, nearly all of Hassel Island, and many acres of coral reef. (See also Virgin Islands National Park, Virgin Islands Coral Reef National Monument, Buck Island Reef National Monument, Christiansted National Historic Site, and Salt River Bay National Historical Park and Ecological Preserve.)
The Virgin Islands lie on the boundary of the North American plate and the Caribbean Plate. Natural hazards include earthquakes, tropical cyclones, and hurricanes.