This Encyclopedia is designed to accumulate and systematize our knowledge about the unique natural water areas - the Laptev, East Siberian and Chukchi seas, their wealth, the events that took place on its waters and shores, and the remarkable people whose lives were and are closely intertwined with the seas. The Encyclopedia contains about 1,500 terms and concepts related to the seas in alphabetical order. It describes geographical features: rivers, lakes, straits, bays; provides information about towns, seaports, transport communications, basic aquatic biological species, nature reserves, national and international programs for the study of the sea, research institutes, historical monuments, activities of prominent explorers and travelers, researchers and scientists. The Encyclopedia also includes a chronology of major historical events connected with the Eastern Arctic seas for more than 400 years.