Simsa Bay – a gulf in the Laptev Sea, on the northeast coast of the Taymyr Peninsula, to the east from Chelyuskin Cape, Taymyr (Dolgano-Nenets) Autonomous Area, Russia. It is narrow with embayed coastline, jutting out into the mainland for 26 km to the southwest. The width of the opening in the sea is 3.5 km, average width around 14 km. In the west, it is divided from a larger Teresa Klavenes Bay by the Lassinius Peninsula. To the north from the Simsa mouth lie the Komsomolskaya Pravda Islands. For administrative purposes, the S. B. belongs to the Krasnoyarsk Territory.
The climate of the gulf is severe, arctic. The gulf is covered with ice most of the year, sometimes remaining frozen even in summer. The coasts of the gulf are covered with moss and lichen tundra. The coasts and water area of the gulf belong to the “Chelyuskin Peninsula” part of the Great Arctic Reserve.
The gulf was named in 1919 by participants of a Norwegian polar expedition on the “Maud” ship headed by R. Amundsen in honor of an American Admiral W. Sims.