Three rivers flow through Olsztyn, the longest of which, the Łyna, discharges itself to the PregolaRiver in Kaliningrad County. The other two watercourses are the rivers Wadąg, constituting a largepart of the northern boundary of the city, and the smallest of Olsztyn rivers – the Kortówka.

The Łyna of the length of 264 km has its origin in the village of Łyna, situated south of Olsztyn,located in the Łyna valley forming an extremely picturesque area, particularly in the northern partof the city. The length of the part of the Łyna which flows through Olsztyn is 13 km, includinga long part through the City Forest, and before that – through the Old Town, beautifully fitting itselfin the landscape of ancient Olsztyn. In many places on the Łyna we can see wild ducks, whichhave taken such a liking for this river that many of them stay in the city for winter.

Regular Canoe rallies «Along the Łynathrough Olsztyn» have been organizedfor several years on the river within thecity (from the park at the Warmia ChapterCastle to the flood waters where the riverWadąg comes together with the Łyna).

The River Wadąg is a right-bank tributaryof the Łyna, around 9 km long andstarting from Lake Wadąg. It flows outof the lake of the same name locatedeast of Olsztyn in the neighbouringcommune of Barczewo. The river confluenceof the Wadąg and the Łyna is oneof the most beautiful places of Olsztyn.

Kortówka is a small river flowingout of Lake Ukiel and through LakeKortowskie and discharging itself to theŁyna in the southern part of the city.