The museum displays Britain’s first submarine, Holland I, and the 1945 A Class submarine HMS Alliance – both of which feature on the Core Collection of UK Historic Ships. The museum also features examples of other large artefacts including submarine rescue craft, human torpedoes from around the world, as well as diving and salvage displays.

The project involved the building of a two-storey extension to the existing main museum building, and conserving and redisplaying the historic X24 midget submarine. The X craft is the only such craft in existence that saw service during the Second World War. It was previously displayed outdoors in two halves but the conservation project has seen it brought under weatherproof cover and undergo restoration work.

The museum now benefits from increased space in order to show more of the collections and broaden both visitor interest and profile. The project also improved visitor facilities with new catering, retail and reception areas, as well as temporary exhibition space and the refurbishment of existing galleries.