In its lower course it flows close to the northwestern side of the Taikan Range into the Uda Bay of the Sea of Okhotsk near the Shantar Islands.

Udsk Ostrog (fort) was founded in 1679,[6] or 1659 [7] on the left bank of the river 76 to 97 kilometres (47 to 60 mi) upstream.

There were suggestions to move Okhotsk south to Udsk but this was rejected because of the poor harbor and the proximity of the Chinese border.

There were generally about 10 peasant families around the fort trying to produce grain and a few thin cattle, but results were poor.

Pack horses were usually left at Udsk as food for sled dogs or people while the Yakut drivers returned to Yakutsk on foot or skis.