Corsair Rock

Meet the site

Corsair Rock is the ship-killer of Port Phillip Heads. The Scuba Doctor listing describes a submerged pinnacle about 6 m across with 3.5 m of water over its kelp-covered top, marking the south-western edge of Nepean Bank at the entrance. On the flood it shows as a swirl on the surface; on a strong ebb it breaks in short seas and white water. It was charted in October 1853 from the pilot cutter Corsair – a vessel that was itself wrecked on Nepean Reef in 1874 – and it has been putting ships ashore ever since: the Ontario and the French ship Marie both in 1853, the Eliza Ramsden in 1875 (she struck here and sank later inside the bay), the barque Craigburn, and most famously the P&O mail steamer RMS Australia, which ran onto the rock in fog in June 1904 and broke up; her plating lies in 3–4 m on the reef about 150 m to the north near Inner Corsair Wall.

Underwater the pinnacle rises from about 30 m on its seaward side, with gutters and ledges cut into its flanks and a flat, kelp-topped summit. The upper rock is scoured by the current and carries kelp and coralline algae rather than the sponge gardens of the walls, but the ledges below 10 m are heavily encrusted, southern rock lobster are numerous, and schools of sweep and old wives hold in the lee. Seals from the Point Nepean colony are frequent. Wreck debris – plating, fittings, ballast – is scattered in the gutters, most of it unattributable.

The dive is about position as much as scenery: being on the rock that shaped the Heads' maritime history, in water that is rarely still. It is dived only on the ebb slack in calm seas and is a club and private-boat site rather than a charter regular. Advanced divers with a competent skipper can circle the pinnacle in the 10–20 m band; the base at 30 m is for the experienced.

What you might see

Kelp and coralline algae on the summit, southern rock lobster, silver sweep, old wife, bluethroat wrasse, southern blue devil, encrusting sponges on the flanks, Australian fur seal, sevengill shark

Location

Submerged pinnacle marking the south-western tip of Nepean Bank at the entrance to Port Phillip, about 1 km west of Point Nepean; 122 m from the Campbell wreck and 150 m south of Inner Corsair Wall.