The Omolon (, Omoloon) is the principal tributary of the Kolyma in northeast Siberia. The length of the river is 1114 km. The area of its basin is 113000 km2. The Omolon freezes up in October and stays under ice until late May through early June. The lower 600 km are navigable.

Course

It begins in the Kolyma Highlands, Magadan Oblast, less than 100 km from the Sea of Okhotsk, flows first northeast, with the Kedon Range to the west, then it bends northwest and forms part of the border of Magadan and Chukotka, with the Yukaghir Highlands to the west. At the western end of the Ush-Urekchen it turns north and crosses Chukotka, briefly enters the Sakha Republic and joins the Kolyma 282 km upstream from the Arctic. Its basin is surrounded by: (west) branches of the Kolyma, (south) Penzhina and others that flow south, (east) Anadyr and (northeast) Bolshoy Anyuy. Its main tributaries are the Kegali, the west-flowing Oloy (at 471 km, the largest tributary), Oloychan, Kedon, Namyndykan, Molongda (Молонгда or Моланджа) and Ango.

Flora and fauna

The upper Omolon is subalpine in the highlands, the middle is boreal forest and the lower part tundra. There is a Zakaznik in Chukotka to protect the forests.