The Sym (Russian: Сым) is a left, western tributary of the Yenisey in Krasnoyarsk Krai, Russia. It is 694 kilometres long, and has a drainage basin of 31,600 square kilometres. It is navigable about 265 km upstream from its mouth.
The Sym begins at a height of 180 m in a swampy area of the West Siberian Plain. It flows roughly southeastwards across flat and often boggy areas, forming increasingly wide meanders. About 50 kilometres before the mouth it bends and flows in a roughly ENE direction, finally joining the left bank of the Yenisey between Yarzevo and Krivlyak.
The river freezes in October or early November and stays frozen until May. Its main tributaries are the Alsym, Kukocha, Oksym and Kolchum.
