The Angrapa is a river that begins in northeastern Poland and ends in the Kaliningrad Oblast of Russia. Originating in Lake Mamry, it joins the 101-km-long Instruch at a point near Chernyakhovsk – variously assessed as lying 140, 169, or 172 km from its source – to form the Pregolya. Its largest tributaries are the 89-km-long Gołdapa, which joins just before the border, and the Pissa.