Chukchi Sea is a marginal sea of the Arctic Ocean. It is bounded on the west by the De Long Strait, off Wrangel Island, and in the east by Point Barrow, Alaska, beyond which lies the Beaufort Sea. The Bering Strait forms its southernmost limit and connects it to the Bering Sea and the Pacific Ocean. The principal port on the Chukchi Sea is Uelen in Russia. The International Date Line crosses the Chukchi Sea from NW to SE. It is displaced eastwards to avoid Wrangel Island as well as the Chukotka Autonomous Okrug on the Russian mainland.
The sea has an approximate area of 595,000 km² (230,000 mi²) and is only navigable about four months of the year. The main geological feature of the Chukchi Sea bottom is the 700 km (435 mi)-long Hope Basin, which is bound to the northeast by the Herald Arch. Depths less than 50 m (164 ft) occupy 56% of the total area.
The Chukchi Sea has very few islands compared to other seas of the Arctic. Wrangel Island lies at the northwestern limit of the sea, Herald Island is located near its northern limit, and a few small islands lie along the Siberian and Alaskan coasts. The sea is named after the Chukchi people, who reside on its shores and on the Chukotka Peninsula. The coastal Chukchi traditionally engaged in fishing, whaling and the hunting of walrus in this cold sea.
The polar bear is found on pack ice of the Chukchi Sea; in fact, the population of polar bears that is found in the sea and its pack ice is one of the five genetically distinct Eurasian populations of this species.
In 2012, scientists from the Cold Regions Research and Engineering Laboratory published findings describing the discovery of the largest-known oceanic phytoplankton algal bloom in the world. The findings were unexpected as it was previously believed that the plankton grows only after the seasonal ice melt, yet some algae was discovered under several metres of intact sea ice.