Platypus which was referred to as "Plats" by the ship's company and was the only dedicated submarine base in Australia. Engineering Workshops, Medical Facilities, the Submarine School, Communications Centre and Administration were all housed at Plats providing the support required for the submarines and their crews to remain operational.
While the submarines operated from the waterfront, the RANís torpedo workshops occupied the southern part of the site.
In 1999, HMAS Platypus and the torpedo workshops closed down when the Commonwealth decided to relocate its submarine base to HMAS Stirling in Western Australia.
The site was handed over to the Sydney Harbour Federation Trust on 23 July 2005, and is currently closed to public access while remediation works of the ground contamination and buildings on the site is undertaken.