This dry limestone isle is the most northerly of the Leeward Islands, lying between the Caribbean Sea and the Atlantic Ocean. The island is only 16 mi (26 km) long and 3 mi (5 km) wide at its widest point. A low-lying limestone island, its highest spot is 213 feet above sea level. Since there are neither streams nor rivers—only saline ponds used for salt production—water is provided by cisterns that collect rainwater or desalinization plants.