(also Chukoch’ia, Revum-Revu), a river in Yakut ASSR. It is 758 km long, drains a basin of 19,800 sq km, and rises from Lake Usun-Kiuel’, flowing through the Kolyma lowland into the East Siberian Sea. Its bed is twisting and 18.2 percent of its basin is covered by lakes. The Bol’shaia Chukoch’ia is fed by snow and rain and reaches its high-water level in June; it freezes over in October, freezes down to the bottom in the winter, and resumes flowing in May. The Savva-Iuriakh, Oler, and Semen-Iuriakh are the main tributaries.