Melbourne's waters hold more than kelp forests and colourful reef life. Beneath the surface of Port Phillip Bay and the surrounding Bass Strait coastline lies a rich maritime history spanning more than a century and a half. From deliberately scuttled warships to tragic merchant vessel losses, the region's seabed is scattered with wrecks that offer some of the most compelling diving experiences in southern Australia. For recreational divers willing to venture beyond the familiar pier sites, wreck diving around Melbourne opens up a world of history, marine ecology, and genuine underwater adventure.
The wrecks accessible from Melbourne range from massive naval vessels sitting upright on sandy bottoms to small coastal traders broken apart by decades of current and storm surge. Some have been intentionally prepared as dive sites and artificial reefs, with hazards removed and mooring lines installed. Others remain largely as the sea claimed them, demanding greater caution and planning. What unites them all is the way marine life has reclaimed these structures — every wreck becomes a reef over time, attracting fish, invertebrates, and the divers who come to see them.
Ex-HMAS Canberra: Australia's Largest Accessible Dive Wreck
The undisputed centrepiece of wreck diving near Melbourne is the Ex-HMAS Canberra, an Adelaide-class guided missile frigate that served in the Royal Australian Navy for over two decades before being deliberately scuttled as a dive wreck and artificial reef on 4 October 2009. At 138 metres in length, she is the largest vessel ever intentionally sunk for recreational diving in Australian waters, and she remains one of the most impressive wreck dives anywhere in the Southern Hemisphere.
The Canberra sits upright on a sandy bottom approximately 2.8 kilometres off Barwon Heads, near Ocean Grove on the Bellarine Peninsula. The top of the superstructure rises to around 15 metres below the surface, while the main deck sits at roughly 22 metres and the seabed surrounding the hull is at approximately 28 metres. This depth range means the wreck is accessible to Advanced Open Water divers, though bottom time at the deeper sections requires careful gas management and dive planning.
Before scuttling, the vessel was extensively cleaned and prepared for safe diving. Hazardous materials were removed, and large openings were cut into the hull to allow diver access and light penetration. Guided penetration of the superstructure is possible, with multiple entry and exit points throughout the ship. Interior spaces include the bridge, passageways, and compartments that retain enough original fittings to give a real sense of the vessel's operational history. The preparation work means penetration diving on the Canberra is considerably less hazardous than on unprepared wrecks, though proper wreck diving training and equipment remain essential.
Since her scuttling, the Canberra has become an extraordinarily productive artificial reef. The hull is now heavily encrusted with sponges, sea squirts, and hydroids. Schools of yellowtail kingfish, snapper, and sweep regularly patrol the structure, while blue devilfish, leatherjackets, and old wives shelter in the crevices and compartments. During the cooler months, large broadnose sevengill sharks are sometimes encountered in the vicinity. The marine colonisation continues to develop year on year, and divers who return to the Canberra regularly remark on how the ecosystem grows with each visit.
Access to the Canberra is by charter boat only, departing from either Queenscliff or Barwon Heads. The wreck lies in waters that can experience significant swell and current, so trips are weather-dependent and cancellations are common during the rougher months. When conditions are right, however, the Canberra delivers a dive that rivals wreck sites anywhere in the world.
The J-Class Submarines: WWI History on the Seabed
For divers interested in military history, the J-class submarine wrecks in Port Phillip Bay represent a genuinely unique experience. Five J-class submarines — J1, J2, J4, J5, and J7 — were scuttled in the Bay in the 1920s after being transferred to the Royal Australian Navy from the Royal Navy following the First World War. These vessels were among the largest and most advanced submarines of their era, and their remains constitute one of the most historically significant collections of submarine wrecks accessible to recreational divers anywhere in the world.
The submarines are scattered across the southern end of Port Phillip Bay at depths ranging from approximately 20 to 30 metres. J1, J2, and J7 lie relatively close together near the Quarantine Anchorage, while J4 and J5 are positioned further apart. The submarines were stripped of useful equipment before scuttling but retain their basic hull forms, and sections of the pressure hulls, conning towers, and internal framing are still identifiable. J7 is generally considered the most intact and most frequently dived of the group.
Diving the J-class submarines is a different experience from the Canberra. These wrecks are over a century old and have deteriorated substantially. Structures are fragile, sharp, and in some cases unstable. Penetration is inadvisable and in many areas physically impossible due to collapse. The primary appeal is external exploration, tracing the outlines of these remarkable vessels and reflecting on the history they represent.
Visibility in the southern reaches of Port Phillip Bay can be challenging. Conditions of 3-5 metres are common, and on poor days visibility can drop below 2 metres. This can make navigation difficult and reduces the visual impact of the wrecks. On the better days, when visibility reaches 8-10 metres, the submarines are atmospheric and memorable dives. Torch lights are essential regardless of conditions, both for navigation and for appreciating the marine growth that covers the hulls.
SS Eliza Ramsden
The SS Eliza Ramsden is a historic cargo vessel that sank in Port Phillip Bay and now rests on the bottom as a popular boat dive destination. The wreck has been colonised extensively by marine life, making it an appealing option for divers who enjoy both the historical context of wreck diving and the biological richness that established wrecks support. Sponge gardens, anemones, and nudibranchs are commonly found across the structure, while schools of fish use the wreck as a gathering point. The Eliza Ramsden sits at a moderate depth that places it within reach of divers with Advanced Open Water certification, and the site is regularly visited by Melbourne's charter operators.
Rotomahana
The Rotomahana is the remains of a paddle steamer that came to grief in Port Phillip Bay. As a paddle steamer wreck, she represents a different era of maritime technology from the naval vessels and cargo ships that make up most of Melbourne's wreck diving. The paddle wheel mechanisms, boiler sections, and hull remnants offer distinctive structural features not found on other local wrecks. The site has been dived for decades by Melbourne's wreck diving community and continues to attract interest from those exploring the Bay's maritime heritage. Marine life is well established on the wreck, with the usual Port Phillip Bay assemblage of sponges, ascidians, and reef fish in residence.
The Casablanca
The Casablanca is a smaller vessel wreck that provides a more compact diving experience compared to the larger sites. While not as imposing as the Canberra or as historically significant as the J-class submarines, the Casablanca offers a manageable wreck dive that can be thoroughly explored in a single dive. The structure provides habitat for a variety of marine life, and the site is sometimes combined with dives on nearby wrecks or reef features as part of a multi-dive charter trip. For divers building wreck diving experience, smaller wrecks like the Casablanca are valuable stepping stones before progressing to more demanding sites.
Lonsdale Wall and Lonsdale Arches
While not a wreck site, the Lonsdale Wall and Lonsdale Arches near The Heads — the narrow entrance to Port Phillip Bay between Point Lonsdale and Point Nepean — deserve mention in any discussion of Melbourne's boat diving. These dramatic underwater geological formations feature sheer walls, swim-through arches, and overhangs that create an experience more commonly associated with tropical dive destinations. The rock faces are covered in colourful sponges, gorgonian fans, and bryozoans, and the area's strong currents support dense populations of fish including large schools of bullseyes and sweep.
Lonsdale Wall and the Arches are frequently offered by the same charter operators that run wreck diving trips, and many divers combine a wreck dive with a Lonsdale dive on the same day. Conditions at The Heads are tide-dependent and can involve strong currents, so these dives require proper planning and are best suited to experienced divers. When conditions align, however, the Lonsdale formations rank among the most visually stunning dive sites in Victoria.
Certification and Training Requirements
Wreck diving around Melbourne demands appropriate certification and experience. As a general minimum, an Advanced Open Water certification is necessary for most wreck sites due to their depths beyond 18 metres. For dives on the Canberra and the deeper J-class submarines, comfort at depths of 25-30 metres is essential, and a Deep Diver specialty or equivalent experience is strongly recommended.
For any wreck penetration — entering enclosed overhead environments within a wreck — a Wreck Diver specialty certification is the minimum standard. This training covers navigation techniques in confined spaces, line-laying procedures, emergency protocols for entanglement and silting, and the psychological aspects of overhead environment diving. Even on the relatively well-prepared Canberra, penetration without proper training and equipment is dangerous and irresponsible.
Nitrox certification is a practical advantage for wreck diving. Enriched air extends no-decompression limits at wreck-typical depths of 20-30 metres, giving you more useful bottom time to explore the site. Most Melbourne charter operators can supply Nitrox fills. If you are planning your training pathway, our seasonal diving calendar can help you time your courses and dives around the best conditions.
Safety Considerations
Wreck diving carries inherent risks beyond those of standard reef diving, and Melbourne's conditions add their own challenges. A responsible approach to safety is non-negotiable.
- Depth and gas management: Most wreck sites sit at 20-30 metres, where air consumption increases significantly and no-decompression limits are measured in minutes rather than hours. Plan your gas supply conservatively, agree turn pressures with your buddy before the dive, and always surface with a comfortable reserve.
- Limited visibility: Port Phillip Bay is not the tropics. Visibility of 3-5 metres is common on the submarine wrecks and can occur on any site. Carry a reliable torch — ideally a primary and a backup — and be prepared to navigate by feel and compass if conditions deteriorate.
- Entanglement hazards: Wrecks accumulate fishing line, nets, and loose cables over time. Carry a cutting device within easy reach at all times. Streamline your equipment to minimise snag points, and avoid dangling accessories, loose hoses, or unsecured gauges.
- Structural instability: Older wrecks like the J-class submarines and Eliza Ramsden have deteriorated significantly. Metal structures may be weakened and unstable. Avoid touching, pulling, or standing on wreck components, and maintain awareness of what is above you at all times.
- Buddy protocols: Stay in close contact with your buddy throughout the dive. Agree on communication signals, lost-buddy procedures, and emergency ascent plans before entering the water. On low-visibility dives, a buddy line can be a sensible precaution.
- Current and surface conditions: Many wreck sites, particularly the Canberra and Lonsdale formations, are exposed to current and swell. Listen to your skipper's briefing, plan for current direction, and be prepared for surface conditions to change during the dive.
Charter Operators for Wreck Diving
Wreck diving around Melbourne is exclusively a boat diving activity, and choosing a reputable charter operator is essential. Several operators run regular wreck diving trips from the Bellarine Peninsula and Mornington Peninsula.
Scubabo is a well-established operator offering trips to the Canberra, the J-class submarines, and other wreck and reef sites around the Bay. They are known for experienced skippers and detailed dive briefings that cover wreck history alongside safety information.
Bay City Charters provides wreck diving trips along with a range of other dive charters in the Port Phillip Bay and Heads area. Their local knowledge of conditions and site selection makes them a reliable choice for both regular wreck divers and those making their first wreck diving trip.
Chimney Rock Diving runs trips to many of the region's wreck and reef sites, including the Canberra and the Lonsdale formations. They cater to divers across a range of experience levels and can advise on site selection based on certification and comfort level.
Booking in advance is recommended for all charter operators, particularly during summer when demand is highest and weather windows attract larger groups. Most operators require proof of certification before the dive and may ask about your experience level to ensure appropriate site selection.
When to Go
Summer (December through February) offers the best overall conditions for wreck diving around Melbourne. Water temperatures reach 17-20 degrees Celsius, weather windows are more frequent and longer, and visibility is generally at its best. The Canberra in particular benefits from calmer summer seas that allow more reliable access to the site.
Autumn and spring can also produce excellent diving days, often with fewer boats and divers on site. Winter diving is possible but conditions are less predictable, water temperatures drop to 10-13 degrees Celsius, and the exposed outer sites like the Canberra are frequently inaccessible due to swell. Proper cold water gear becomes essential for comfortable wreck diving outside the summer months.
Regardless of season, calm weather is essential for the deeper and more exposed wreck sites. Monitor forecasts closely in the days before your planned dive, and be prepared for last-minute changes or cancellations. Flexibility with dates dramatically increases your chances of getting onto the water.
Photography on Wrecks
Wreck diving offers outstanding photographic opportunities, but the environment demands some specific considerations. A wide-angle lens is essential for capturing the scale of larger wrecks like the Canberra. At Melbourne's typical visibility, you may be working at distances of 2-5 metres, so a fisheye or rectilinear wide-angle in the 10-17mm range (full-frame equivalent) will serve you best for structural shots.
Lighting is critical, particularly for interior spaces. Ambient light drops off rapidly inside wreck structures, and Melbourne's green-tinged water absorbs colour quickly. External strobes restore colour and contrast to wide-angle images, while a focusable torch or video light is useful for painting light into darker compartments. Backscatter is a constant challenge in Port Phillip Bay's particulate-rich water — position strobes wide and angled outward to minimise the problem.
For macro subjects on wrecks, the encrusting marine life provides abundant material. Nudibranchs, decorator crabs, and juvenile fish sheltering among sponge growth are all rewarding subjects. A dedicated macro dive on a well-colonised wreck can be just as productive as any reef site.
Conservation and Heritage Protection
Wreck sites in Victorian waters are protected under both state and federal heritage legislation. The Heritage Act 2017 (Victoria) and the Underwater Cultural Heritage Act 2018 (Commonwealth) establish legal frameworks for the protection of shipwrecks and their associated artefacts. The practical implications for divers are straightforward but important.
- Do not remove artefacts. It is an offence to remove, disturb, or damage any material from a protected wreck site. This includes seemingly insignificant items such as fragments of pottery, glass, metal fittings, or coal. Penalties can be substantial.
- Do not disturb the wreck structure. Avoid unnecessary contact with wreck components. Fin kicks that dislodge encrusted material or destabilise corroded sections cause cumulative damage over time.
- Report significant finds. If you observe something unusual — previously unexposed sections, undocumented features, or signs of unauthorised interference — report it to Heritage Victoria or the relevant charter operator.
- Respect the memorial nature of wreck sites. While the prepared dive wrecks like the Canberra were deliberately sunk, many historic wrecks are the final resting places of those who were aboard. Treat all wreck sites with appropriate respect.
As divers, we are privileged to access these sites. Responsible diving practices ensure that wreck sites remain intact and available for future generations of divers and marine researchers. Take only photographs, leave only bubbles, and carry the history you discover back to the surface as stories worth sharing.
Ready to explore Melbourne's underwater history? Check the Boat Dives page for current conditions and start planning your next wreck diving adventure.