HMAS J1 Submarine

HMAS J-Class Submarines, Bass Strait

By ScubaDownUnder Team · 2026-09-11

Out in Bass Strait, beyond the entrance to Port Phillip, lies a graveyard of submarines. Several of the Royal Australian Navy's J-class boats, built for the First World War, were towed out and scuttled here in 1926, and they have rested on the bottom ever since, slowly turning into reefs. The J-class submarines are among the most atmospheric and serious wreck dives in Victoria: deep, cold and historic, draped in sponge and zoanthid, and demanding of the divers who visit them. They are not a casual dive, but for those equipped for them, they are unforgettable.

The J-class submarines were transferred to the Royal Australian Navy after the First World War, briefly among the most powerful submarines in the southern hemisphere, but they were ageing and expensive, and by the mid-1920s they had been decommissioned. In 1926 most were towed out through Port Phillip Heads and scuttled in the Victorian Ships' Graveyard off Barwon Heads, while the J3 was sunk at Swan Island to serve as a breakwater. The scuttled boats settled into Bass Strait at a range of depths, and over the decades they have become both artificial reefs and a focus for Victorian wreck divers drawn to their history.

The submarines lie at different depths, which makes them a graded set of dives. The shallowest, the J4, sits in around nineteen to twenty-eight metres, its bow broken away in the scuttling to expose the forward torpedo tubes, which divers can examine without penetrating the hull. The J5, the so-called Yellow Submarine, lies in twenty-five to thirty-six metres, the most intact of them and famously coated in yellow zoanthids. The J2 and the deep J1 lie deeper still, the J1 reaching thirty-one to thirty-eight metres. These are decompression-range dives in cold, sometimes current-swept water, with run times around fifty-five minutes, and they have claimed divers over the years, so they are firmly the domain of experienced and well-prepared wreck divers.

Decades on the bottom have turned the steel into reef. The hulls are encrusted with sponges, soft corals and the zoanthids that give the J5 its yellow nickname, and the structure shelters the temperate fish of Bass Strait. Schools of bullseyes and baitfish hang over the wrecks, leatherjackets and morwong work the hulls, and southern rock lobster back into the broken sections. The marine growth is dense in the cold, nutrient-rich water, so the submarines are as rewarding for their reef life as for their history, the grey steel softened by colour.

These are serious cold-water wreck dives. Water temperature ranges from around 11°C in winter to 19°C in late summer, drysuit territory, and visibility is variable, often in the five to twenty metre range and best in settled conditions. The wrecks lie in open Bass Strait beyond the Heads, exposed to swell, and current can run, so they are dived on slack water in calm weather. The depths put the deeper boats squarely in decompression and technical territory, with the shallower J4 the most accessible. Penetration of the hulls is an overhead environment for properly trained and equipped divers only. Careful gas planning, redundancy and conservative profiles are not optional here.

For Victorian wreck divers, the J-class submarines are a rite of passage and a graded progression, from the broken bow of the J4 to the intact, deeper J5 and J1. The combination of genuine naval history, the eerie shapes of the submarines on the bottom and the rich marine growth gives the dives a strong pull. Technical-capable operators run them out of the Port Phillip Heads ports when the conditions line up, often pairing them with the other deep wrecks of the ships graveyard.

The J-class submarines are a reminder that some of Australia's most compelling diving is also its most demanding. The WWI boats, scuttled and forgotten, now lie in the cold green water of Bass Strait, wearing reef and history in equal measure. For the experienced divers who earn their way down to them, they are among the great wreck dives of the south.

## Site Access and Logistics

The J-class submarines lie in Bass Strait, in the Victorian Ships' Graveyard off Barwon Heads and Port Phillip Heads, reached by boat from the Heads ports such as Queenscliff and Portsea. There is no shore access, and the wrecks are dived by charter operators equipped for deep, technical diving, when slack water and calm weather coincide.

These are advanced and technical dives. The shallower J4, at around nineteen to twenty-eight metres, is within reach of experienced deep recreational divers, but the J5, J2 and J1 lie in decompression range to around thirty-eight metres and demand technical training, appropriate gas, redundancy and disciplined planning. Penetration of the hulls is for trained wreck divers only. A drysuit suits the cold water, a surface marker buoy and decompression capability are standard, and the wrecks are dived on slack water given the current and exposure. These dives have a real safety history, so honest self-assessment matters.

Charters to the J-class submarines run from the Port Phillip Heads ports, including through [The Scuba Doctor](https://www.scubadoctor.com.au/j-class-submarine-wreck-dives.htm).

## Sources

- The Scuba Doctor, J Class submarine wreck dives: [https://www.scubadoctor.com.au/j-class-submarine-wreck-dives.htm](https://www.scubadoctor.com.au/j-class-submarine-wreck-dives.htm) - Divernet, the hidden treasures of Victoria's J-class submarines: [https://divernet.com/scuba-diving/discover-the-hidden-treasures-of-victorias-j-class-submarines/](https://divernet.com/scuba-diving/discover-the-hidden-treasures-of-victorias-j-class-submarines/) - The Scuba Doctor, J1 Deep Submarine: [https://www.scubadoctor.com.au/diveshop/index.php?main_page=divesite&site=J1-Deep-Submarine](https://www.scubadoctor.com.au/diveshop/index.php?main_page=divesite&site=J1-Deep-Submarine) - The Scuba Doctor, J5 Yellow Submarine: [https://www.scubadoctor.com.au/diveshop/index.php?main_page=divesite&site=J5-Yellow-Submarine](https://www.scubadoctor.com.au/diveshop/index.php?main_page=divesite&site=J5-Yellow-Submarine) - The Scuba Doctor, J4 26m Submarine: [https://www.scubadoctor.com.au/diveshop/index.php?main_page=divesite&site=J4-26m-Submarine](https://www.scubadoctor.com.au/diveshop/index.php?main_page=divesite&site=J4-26m-Submarine)