Laptev Sea (Russian, More Laptevykh), part of the Arctic Ocean, off the northern coast of Siberian Russia. The Taymyr Peninsula is to the west, and the New Siberian Islands (Russian, Novosibirskiye Ostrova) are to the east. The sea is frozen for much of the year. Tiksi, near the mouth of the Lena River, is the chief port. The Laptev Sea is named after the 18th-century Russian cousins Khariton and Dmitri Laptev, who explored and mapped its shores.