Meet the site
Gem Pier is Williamstown's original pier, a 145 m timber and concrete structure on Nelson Place that has been receiving ships since the 1830s and is among the oldest marine constructions in Victoria. It is now the berth for the Williamstown ferry, tourist cruises and the museum ship HMAS Castlemaine, and it is dived rarely and mostly by locals who want structure within sight of the city. The dive is a silt dive. The bottom of Hobsons Bay here is fine Yarra mud that lifts at the slightest touch, and the golden rule of the site is to stay a metre above it; visibility is generally poor and a careless fin kick makes it nil. The pylons are the attraction: old timber and concrete piles crusted with mussels, oysters, sea squirts, tubeworms and sponges, sheltering Tasmanian blennies, southern cardinalfish, gobies, small leatherjackets and toadfish, with decorator crabs, sea stars, nudibranchs and the occasional octopus or seahorse for those who look closely, and the introduced Northern Pacific seastar and European fan worm much in evidence. Depth runs from about a metre at the shore to 5 m at the head. The historical setting, with the Castlemaine alongside and the wooden boats of the Williamstown waterfront overhead, is much of the point. Practically, it is a site for calm, dry weather at high tide in winter, with careful attention to ferry movements at the berth. Divers wanting cleaner water and more life go 1 km south to the Point Gellibrand rock pools or 2 km west to Williamstown Beach and the Jawbone.
What you might see
Tasmanian blennies, southern cardinalfish, gobies, leatherjackets, toadfish, decorator crabs, sea stars, nudibranchs, octopus, seahorses (occasional); mussels, oysters, sponges, sea squirts and tubeworms on piles; introduced Northern Pacific seastar and fan worm
Location
145 m historic pier on the Hobsons Bay waterfront at Williamstown, beside Commonwealth Reserve and the ferry terminal, one of the oldest marine structures in Victoria.
Facilities nearby
Metered parking on Nelson Place; public toilets at Commonwealth Reserve; cafes and pubs along Nelson Place; nearest air fills Dive Victoria Group
Before you make plans
Conditions, access and operator schedules can change. This is a location guide, not a dive plan. Ask a local operator about current conditions and suitability for your training and experience.
Sources & further reading
scubadoctor.com.auscubadoctor.com.auRecord updated 26 Sept 2026. Source claims are being reviewed.