Severomorsk, known as Vayenga (Ваенга) until April 18, 1951, is a closed town in Murmansk Oblast, Russia. Severomorsk is the main administrative base of the Russian Northern Fleet. The town is located on the coast of the Barents Sea along the Kola Bay 25 kilometers (16 mi) northeast of Murmansk, the administrative centre of the oblast, to which it is connected by railway and a motorway.

A closed city or town is a settlement where travel or residency restrictions are applied so that specific authorization is required to visit or remain overnight. Such places may be sensitive military establishments or secret research installations that require much more space or internal freedom than is available in a conventional military base. There may also be a wider variety of permanent residents, including close family members of workers or trusted traders who are not directly connected with clandestine purposes.