Grewingk Glacier is a 13-mile-long (21 km) glacier located in the Kenai Mountains, near Kachemak Bay, in the U.S. state of Alaska. A glacier is a persistent body of dense ice that is constantly moving under its own weight; it forms where the accumulation of snow exceeds its melting and sublimation over many years, often centuries. Glaciers cover about 10 percent of Earth’s land surface and are the largest reservoir of fresh water on earth.