Sarushima (猿島, "Monkey Island"), is a small island located off Yokosuka, Kanagawa in Japan.

Sarushima was used as a battery by the Tokugawa shogunate during the Edo period, and after the Meiji Restoration in 1868, the island was developed as part of the Yokosuka Navy Yard.

[3] Sarushima is now uninhabited, and after World War II, it was developed as a marine park.

Swimming and camping facilities were built on Sarushima, which makes it a popular fishing spot.

The highest part of the island is still surrounded by a stone wall from the pre-war period, and features the remains of red brick barracks and a powder magazine.