Buninyong was built by Laird, Purdie and Co at Barrow-in-Furness in 1883 as a 2,076-ton, 85 m (280 ft) passenger and cargo steamer for the intercolonial trade between Melbourne, Sydney and Adelaide, one of a generation of steel liners that made the coastal passage comfortable for the first time. Passenger fashions moved on; in 1913 she was refitted as a collier and worked the Newcastle coal run until she was worn out. She was scuttled in the Graveyard on 11 February 1926, one of the earliest of the officially recorded dumpings.

The wreck lies in 50–54 m with the bow facing Barwon Heads at the deepest point. It is the second-largest vessel in the Graveyard after the Milora and a proper ship to explore: the bridge is still intact, with an exhaust stack fallen across it, and three boilers remain in place – two large units amidships and a smaller one towards the stern. The hull has opened out in the usual Bass Strait way but there is still height and a recognisable ship shape, and the boilers and bridge give shelter to ling, boarfish, bullseyes and crayfish.

Sponge growth is good because the site is well clear of the Barwon plume, and visibility of 15 m or more is common in autumn. This is a mixed-gas dive: the Scuba Doctor notes it is favoured by trimix divers, and there is nothing worthwhile shallower than about 44 m. It is visited only a few times a year by technical charters and private boats, so expect an unshotted, unbuoyed wreck and plan to find it with a sounder and a weighted shot.

For technical divers who have done Milora and the Batman group, Buninyong is the logical next step in scale and depth, offering a genuine sense of an intact liner rather than a debris field.

Boat only. Charters leave from Queenscliff Harbour (Red Boats, Dive Victoria Group) or Portsea Pier (Dive Victoria Group, Bayplay); drive Melbourne–Queenscliff via the Geelong Ring Road and Bellarine Highway (about 1 h 40 min) or Melbourne–Portsea down the Mornington Peninsula Freeway (about 1 h 45 min). Private boats launch at Queenscliff (Larkin Parade) or Sorrento ramps; the wreck lies a few kilometres outside The Rip, so time the run through the Heads for slack or a following tide.

Boat time from Queenscliff is roughly 20–30 minutes and from Portsea 30–40 minutes in a fast RIB, longer in a displacement charter boat. Gear is loaded at the harbour; there is parking at Queenscliff Harbour and along Point Nepean Road at Portsea.

Fully exposed Bass Strait. South-westerly swell is the killer: most charters will not run on a forecast over about 1.5 m, and anything from the south or west over 2 m makes the site undiveable and the passage through The Rip dangerous. Northerly and north-easterly winds flatten the sea; a calm morning after several settled days gives the best visibility (often 15–25 m in autumn and winter).

Surge is felt on the wreck in any swell over 1 m. Tidal streams outside The Heads are weaker than inside but still run; charters aim for slack water at Port Phillip Heads or a favourable tide for the transit. Winter westerlies close the site for weeks at a time.

The wreck sits in or near the shipping approach and pilot boarding ground, so a shot line, surface cover and a delayed SMB are mandatory.

Shot onto the bridge/boiler area. Inspect the intact bridge with its exhaust stack lying across it, then move forward over the two large boilers to the bow, which points towards Barwon Heads at maximum depth (54 m). Return past the smaller third boiler toward the stern if time allows, but with 20 minutes at 50 m most teams cover the midships only.

Ascend the shot with staged deco.

Technical (decompression) dive. Trimix only (18/45 or 15/55) with EAN50 and oxygen deco; a 20 min bottom time typically needs 45–60 min of staged decompression. CCR-friendly with a bailout plan sized for the full ascent.

Drop a weighted shot on the wreck, use a delayed SMB from the wreck or a decompression trapeze under the boat; the site is in a shipping approach so free-drifting deco is discouraged.

No scheduled recreational charters. Red Boats (Queenscliff) and Dive Victoria Group run technical charters to the deep Graveyard wrecks on request or a few times a season for Melbourne technical clubs; otherwise private technical boats only. Expect the wreck to see only a handful of dives a year.