The HMAS J2 is a decommissioned Royal Australian Navy submarine sitting upright on the seafloor off Victoria at 37 to 39 metres, making this firmly deep diving territory. The wreck is largely intact, and the combination of confined spaces, potential low visibility down to 1 metre, cold water, and overhead environments demands solid buoyancy control and prior wreck experience. Visibility can reach 10 metres on a good day, but plan for less. Wobbegong sharks rest against the hull, blue devilfish tuck into crevices, and crayfish shelter beneath overhangs. Schools of fish work the water column above, while benthic invertebrates colonise most exposed surfaces. Mild current is typical, though conditions can strengthen.

The HMAS J5 is one of Victoria's few diveable submarine wrecks, sitting upright on the sand at 34 to 36 metres. The confined spaces and overhead environment demand solid buoyancy control and a technical mindset before you descend. Visibility runs 5 to 10 metres, and moderate current can push through the site, so plan your entry accordingly. The hull is colonised by yellow zoanthids, which provide striking colour contrast against the steel. Seals occasionally visit, adding an unpredictable element to the dive. Nitrogen narcosis is a real consideration at this depth, and decompression obligations can accumulate quickly if you push your bottom time.

The SS Coogee sits in deep diving territory at 32 to 35 metres, making this a shore-entry wreck dive best suited to beginners who have already completed some deeper dives with a guide or instructor. Visibility can reach 15 metres, though conditions vary. The wreck itself hosts a colourful mix of marine life including yellow zoanthids, sponges, cuttlefish, catsharks, and the striking blue devilfish. Old wives, butterfly perch, large-toothed beardy, and crayfish are also regularly spotted around the structure. Be aware that currents here can be extreme, and cold water, surge, and boat traffic all require careful attention. Dive with an experienced operator and plan your bottom time conservatively.

The HMAS J1 sits on the seabed off Victoria as one of Australia's few diveable submarine wrecks, resting at 35 to 36 metres in deep diving territory. The hull is colonised by yellow zoanthid corals and attracts various fish, but the wreck demands respect before you descend. Strong currents run across the site, and the overhead environment inside creates genuine entanglement and navigation risks. Visibility runs 10 to 15 metres, which is workable, but cold water and depth mean your bottom time is short and decompression planning is non-negotiable. Boat charter with a guided tour is the sensible way to approach this one.

The HMAS J4 is one of Australia's few diveable submarine wrecks, sitting upright on the seabed in Victoria's deeper coastal waters at 26 to 27 metres. The hull is well encrusted with kelp and seaweed, giving it a distinctly austere, overgrown character. Visibility ranges from 5 to 15 metres depending on conditions, and strong currents are a consistent feature here, demanding solid buoyancy control and careful dive planning. Surge compounds the challenge near the wreck itself, and entanglement risks from growth and structure mean penetration attempts are not appropriate. This is a boat-access site best suited to experienced wreck divers comfortable in variable, demanding conditions.

Castle Rock is a boat-access reef dive off Victoria that demands respect from the moment you hit the water. Strong currents and surge are the defining conditions here, so solid buoyancy control and situational awareness are non-negotiable. Depths run from 15 to 20 metres with visibility ranging from 5 to 15 metres depending on conditions. The reef holds a good mix of species: Southern Blue Devils occupy crevices alongside crayfish and octopus, while nudibranchs and yellow zoanthids reward anyone who slows down to look closely. Cuttlefish are a reliable sighting, and seals occasionally pass through. Cold water is the norm, so plan your exposure protection accordingly.

Lonsdale Arches is a boat-access reef and cave system in Victoria's Port Phillip Heads, where strong currents shape both the dive and the marine life you'll encounter. Depths run from 10 to 18 metres with visibility reaching 10 to 15 metres on good days. The arches and cave structures provide shelter for Southern Blue Devil fish and crayfish, while soft corals and sponges coat the rock surfaces alongside sweeping kelp. Current management is the core skill here - plan your dive around the tide and be prepared for boat traffic in this busy waterway. Cold water and surge in the caves demand attention.

Dragon's Lair is a boat-access reef dive off Victoria that earns its advanced rating through moderate currents and visibility that typically runs 5 to 10 metres. Working depths of 12 to 18 metres give you a reasonable bottom time, but the current demands solid buoyancy control and a good pre-dive briefing on conditions. The reef supports a range of local species, and the slightly challenging visibility adds a searching quality to the dive that rewards patient, methodical divers. Time your descent to work with the current rather than against it, and you'll get far more out of the site.