The Łyna (Polish pronunciation: [ˈwɨna]; German: Alle [ˈalə] ⓘ; Lithuanian: Alna; Russian: Ла́ва - Lava), is a river that begins in northern Poland's Warmian-Masurian Voivodeship and ends in Russia's Kaliningrad Oblast.

The river's source is located near the village of Łyna in Masuria, Poland.

In historical terms, the river fell within the area of the medieval Monastic state of the Teutonic Knights established in the 13th century.

In 1454, the adjacent territory was incorporated by King Casimir IV Jagiellon to the Kingdom of Poland upon the request of the anti-Teutonic Prussian Confederation.

Following Germany's defeat in World War II, in 1945, it was split between Poland and the Soviet Union in accordance with border changes promulgated at the Potsdam Conference.