The shoalest seas in the Arctic ocean are the Laptev Sea and East Siberian Sea, they are also the coldest in Russian Arctic. During 9-10 months these seas are totally covered with ice in 1.5-2m. In winter the water temperature under the ice cover waggles from –0.8º C in the river mouths to –1.8º C at the northern seaboards. In summer the surface water temperature in bays achieves +10º C, rarely- +14º C, in the high sea is -1º C.