Dive with marine life · 2026 guide
Tens of thousands of crabs piling into the shallows of Port Phillip Bay to moult, in one of Victoria's strangest dives.
Aggregations typically occur around late autumn and early winter, most often May to July. Timing shifts year to year and is not perfectly predictable.
These 3 sites are where giant spider crab encounters are best documented, with the operators who dive them.
1Mornington Peninsula, Victoria
Victoria's most popular pier dive, and the best-known site for giant spider crab aggregations.
It is best known internationally for the giant spider crab aggregation, when tens of thousands of crabs gather in the shallows to moult.
Look for: Giant Spider Crab, Nudibranchs, Seahorses & Pipefish, Weedy Seadragon
Full Blairgowrie Pier guide →
2Mornington Peninsula, Victoria
A shallow, sheltered pier known for seahorses, seadragons and night diving.
The piles and surrounding sand hold seahorses, weedy seadragons, octopus and an excellent range of macro subjects, and the site is heavily used for training.
Look for: Giant Spider Crab, Nudibranchs, Seahorses & Pipefish, Weedy Seadragon
Full Rye Pier guide →3Melbourne, Victoria
The bay's network of pier dives — the accessible heart of Victorian diving.
They provide access to seahorses, weedy seadragons, rays, squid, crustaceans and dense macro life, often in only a few metres of water.
Look for: Giant Spider Crab, Seahorses & Pipefish, Weedy Seadragon
Full Port Phillip Piers guide →Sites are chosen from our dive-site database and ordered by how well documented they are: flagship status, the number of operators we have confirmed dive there, and the marine life recorded. Nobody pays to be listed.
No. Listings and order come from our research only. Businesses can ask us to correct their details, but not to change their position.
It is generated from the directory's latest research, checked in 2026. Conditions, operators and seasons change — confirm details with the operator before you book.