Mývatn, shallow lake, northern Iceland, 30 miles (48 km) east of Akureyri, drained by the Laxá River, which flows northward to the Greenland Sea. Nearly 6 miles (9.5 km) long and 4 miles (6.5 km) wide and covering an area of 14 square miles (37 square km), it is the fourth largest lake in Iceland. It attracts many tourists. Mývatn is dotted with volcanic islands and is surrounded by numerous craters, hot springs, and a variety of lava formations. The lake and the river draining it are noted for salmon, trout, and char fishing. Diatomaceous earth is mined from the lake bottom and processed nearby.