The island was originally a rocky outcrop, but in 1931-2 it was increased in size over seven times by land reclamation, and reshaped into the general plan form of a ship.

[3] In 1879, Snapper Island was declared a public recreation reserve by the NSW Legislative Assembly.

[1][3] In 1930, Len Forsythe leased the island from the Commonwealth Government in order to create a training depot for boys in nautical skills.

[3] With the onset of World War II, the island was returned to the service of the Navy.

Opened after 1966, the museum held thousands of pieces of memorabilia from Australia's naval history.