Hygeia was the finest excursion paddle steamer ever to work Port Phillip. Built on the Clyde at Yoker (Glasgow) in 1890 for the Bay Excursion Company, she was 91 m long, 986 tons, licensed for 1,600 passengers and capable of 23 knots – regarded as one of the fastest and best-appointed paddlers in Australian service. From December 1890 she ran day trips from Melbourne to Queenscliff and Sorrento, the summer institution of a generation of Melburnians, in competition with the Ozone and Weeroona.

Motor cars and the Depression ended the trade; she was sold to a ship-breaker in May 1931 for about £600, stripped, and scuttled on 10 June 1932. The wreck lies in 58–62 m in the shipping approach to Port Phillip, and that location, more than the depth, is why it is so rarely dived. The attraction is obvious: the two great paddle wheels, the only intact examples on a diveable Victorian wreck, still stand in their sponsons amidships, and the bow and stern sections are also worth inspecting.

Between them the long, shallow-draught iron hull has opened out. Deep-water sponges, ling and crayfish have colonised the machinery, and on the rare calm days visibility can exceed 20 m. Diving the Hygeia means a trimix or rebreather team, a full hour or more of decompression hanging in a shipping lane, and a boat skipper prepared to coordinate with Port Phillip Sea Pilots and VTS.

That is why most experienced Victorian technical divers have not done it. For those who do, it is one of the most evocative wrecks in the state – a piece of Melbourne social history rather than a working collier.

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 paddle-wheel area amidships; spend the bottom time on the two paddle wheels and sponsons, extending to the bow or stern if visibility allows, then ascend the shot with staged decompression. Because the wreck is in the shipping approach, a surface vessel must remain on station on the shot and monitor VHF for ship movements throughout the deco.

Technical (decompression) dive. Hypoxic or near-hypoxic trimix (e.g. 15/55 or 12/60) with EAN50 and oxygen; 15–20 min bottom time means 60–90 min of decompression. Rebreather divers dominate here; open-circuit needs multiple stages and a support boat with in-water support.

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. Coordinate with VTS/Port Phillip Sea Pilots before diving; dive only with a dedicated surface vessel on station.

No regular operator. The Scuba Doctor notes the Hygeia 'is not dived very often because it's in the shipping channel'; visits are by private technical boats or a specially arranged technical charter coordinated with port traffic.