Ozyorsk (Russian: Озёрск, until 1938 German: Darkehmen; Polish: Darkiejmy; Lithuanian: Darkiemis; from 1938 to 1946 German: Angerapp) is a town and the administrative center of Ozyorsky District in Kaliningrad Oblast, Russia, located on the Angrapa River near the border with the Polish Warmian-Masurian Voivodeship, 120 kilometers (75 mi) southeast of Kaliningrad, the administrative center of the oblast.

[8] Before the arrival of the Teutonic Order, the river valley was here settled by the Nadruvians, as evidenced by traces of settlements and fortifications found in the area.

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

Located in the transitional area between Masuria in the south and Lithuania Minor in the north, the town and surrounding villages had a mixed population with both many Poles[11] and Lithuanians.

An influx of immigrants followed (in 1725, 103 of the 742 registered inhabitants came from Salzburg) and craft production of leather and cloth established in the town.

[13] Due to its location on the Angrapa River, a power station established in the watermill was already in 1880 able to produce electrical light for the town.

[16] After Germany's defeat in World War II, the town initially passed to Poland under its historic Polish name Darkiejmy, however, it was soon annexed by the Soviet Union.