| En Name: | Ostrovnoy |
| Ru Name: | Островной |
| Coordinates: | 68.05°N 69°W |
| Map Label Position: | left |
| Image Coa: | Ostrovnoj gerb.png |
| Federal Subject: | Murmansk Oblast |
| Adm City Jur: | closed administrative-territorial formation of Ostrovnoy |
| Adm Ctr Of: | closed administrative-territorial formation of Ostrovnoy |
| Inhabloc Cat: | Town |
| Urban Okrug Jur: | Ostrovnoy Urban Okrug |
| Mun Admctr Of: | Ostrovnoy Urban Okrug |
| Leader Title: | Mayor |
| Leader Name: | Gennady Chistopashin |
| Pop 2010Census: | 2171 |
| Prev Name1: | Murmansk-140, Gremikha |
| Postal Codes: | 184640 |
| Dialing Codes: | 81558 |
| Website: | http://www.zato-ostrov.ru |
Ostrovnoy (Russian: Островно́й), previously known as Murmansk-140 (Russian: Му́рманск-140),[1] is a closed town in Murmansk Oblast, Russia. As of the 2010 Census, its population was 2,171; down from 5,032 recorded in the 2002 Census.
The first naval base was established here in 1915. There is no rail link to Ostrovnoy and the settlement is reachable by coastal ship, helicopter or small plane in winter.
Until 1938, the town was known as Yokanga. Until 1981, the town was known as Gremikha.[2]
The Gremikha Naval Base was one of the Northern Fleet's main facilities for servicing nuclear submarines.
Within the framework of administrative divisions, it is, together with six rural localities, incorporated as the closed administrative-territorial formation of Ostrovnoy—an administrative unit with the status equal to that of the districts.[3] As a municipal division, the closed administrative-territorial formation of Ostrovnoy is incorporated as Ostrovnoy Urban Okrug.[4]