The continental runoff into the East Siberian Sea is relatively small at about 250 km3/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 km3, followed by the Indigirka River at 59 km3. 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 11,430 km3, respectively; while the respective inflow values are 3,240, 8,800 and 9,230 km3.