Laptev Sea (Russian More Laptevykh), part of the Arctic Ocean, off the northern coast of Siberia 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 for the 18th-century Russian cousins Khariton and Dmitri Laptev, who explored and mapped its shores.