East Siberian Sea runoff into the East Siberian Sea is relatively small at about 250 km/year that makes only 10% of the total runoff in all the Arctic seas of Russia. The largest contribution is from the Kolyma River at 132 km, followed by the Indigirka River at 59 km. Most runoff (90%) occurs in summer; it is concentrated near the coast, owing to the weak river currents, and therefore does not significantly affect the sea hydrology. The water exchange between the neighboring seas is as follows. The annual outflow to the Laptev Sea, Chukchi Sea and Arctic Ocean is 3,240, 6,600 and
East Siberian Sea southern limits. There are no islands in the middle of the East Siberian Sea, but there are a few islands and island groups in its coastal waters, like Ayon Island and the Medvyezhi island group. The total area of the islands is only 80 km. Some islands mostly consist of sand and ice and gradually erode. The total catchment area is 1,342,000 km. Among the rivers flowing into the East Siberian Sea, the Indigirka, Alazeya, Uyandina, Chukochya, Kolyma, Rauchua, Chaun, and Pegtymel are the most important. Only a few rivers are navigable. The coastline of the sea is 3,016 km