World War II: About 3,000 inmates from the Stutthof concentration camp are forcibly marched into the Baltic Sea at Palmnicken (now Yantarny, Russia) and executed.

Stutthof was a Nazi concentration camp established by Nazi Germany in a secluded, marshy, and wooded area near the village of Stutthof 34 km (21 mi) east of the city of Danzig (Gdańsk) in the territory of the German-annexed Free City of Danzig. The camp was set up around existing structures after the invasion of Poland in World War II and initially used for the imprisonment of Polish leaders and intelligentsia. The actual barracks were built the following year by prisoners. Most of the infrastructure of the concentration camp was either destroyed or dismantled shortly after the war. In 1962, the former concentration camp with its remaining structures was turned into a memorial museum.

The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by the countries of Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden, and the North and Central European Plain regions. It is the world's largest brackish water basin.

Yantarny is an urban locality in Kaliningrad Oblast, Russia, located on the Sambian Peninsula, about 40 kilometers (25 mi) from Kaliningrad, the administrative center of the oblast. Population: 5,524 (2010 Census); 5,455 (2002 Census); 4,948 (1989 Soviet census).