The site was a slightly unusual location for a hospital because it was surrounded by the Gosport Creek, with no readily available access: such an area was chosen to prevent press-ganged sailors from absconding.

There is a mass grave of 42 officers and men of the submarine HMS L55, recovered from the Baltic Sea and repatriated in 1928, their names on a screen wall memorial.

[2] Also now buried here are 26 Turkish sailors of two ships of the Ottoman Navy, Mirat-ı Zafer and Sirag-i Bahri Birik, anchored off the Hardway near Gosport in 1850–51, during which time some of the members of the crew contracted cholera and were admitted to Haslar Hospital for treatment, where most of them died.

In 1802 an infantry barracks was built on a triangular site, on the promontory south of the hospital, which was known as Camp Field (having served as an Army encampment in the latter part of the 18th century).

A small stationary steam engine mounted on the traverser platform drove an endless screw, which was then used to slide the boat back into its shed.

After a series of expansions and contractions, as gunboats went in and out of vogue in naval circles, the Yard closed in 1906; but from 1912 to 1973 the site continued to provide storage and maintenance facilities for small vessels of various types.

The buildings are all of red brick, as is the surrounding perimeter wall, built with integrated watch towers to provide extra security.

Alongside the Gunboat Yard, within the same compound, stands the Admiralty Experiment Works (later part of the Defence Research Agency and now owned by QinetiQ).