HMAS Canberra was an Adelaide-class (US FFG-7 Oliver Hazard Perry design) guided-missile frigate, 138.1 m long, 4,200 tonnes, built by Todd Pacific Shipyards in Seattle, launched on 1 December 1978 and commissioned on 21 March 1981. She served the Royal Australian Navy for 24 years from Sydney and then Fleet Base West, including Gulf deployments and border protection work, and was decommissioned on 12 November 2005. Handed to the Victorian Government for an artificial reef, she was stripped of her gas turbines, missile launcher, propeller, rudder and part of the mast, cleaned to strict environmental standards and cut with access holes, and at 2 pm on Sunday 4 October 2009 was scuttled in front of thousands of spectators off Ocean Grove.

She sits on a sand bottom at 28–32 m heading 210° with a starboard list of about 25°, remarkably intact and level. Depths on the wreck are generous for a ship this size: the bridge roof is 7.7 m, the mid and aft mast bases 7 m, the bow 15 m, the stern and flight deck around 20 m and the sand 28–32 m, so a whole dive can be spent between 10 and 20 m. The bridge, captain's cabin, galley, mess decks, junior sailors' mess with its mural and the operations room are all accessible through the pre-cut openings, and multiple X-marked hull breaches from the scuttling charges open decks 3 and 4 to the light.

Penetration was designed to be relatively safe but the ship is enormous and disorienting; local guides reckon twenty dives to know her. Sixteen years of colonisation have turned an alloy-and-steel warship into a reef: the superstructure is furred with sponges, hydroids, jewel anemones and zoanthids, and the wreck holds dense schools of bullseyes, butterfly perch, sweep and old wives, with boarfish, leatherjackets, wrasse, nudibranchs and cuttlefish inside, and seals and dolphins on the surface. The Canberra is the most-dived site in Victoria and the centrepiece of the state's wreck diving.

It suits everyone from freshly certified divers on a guided tour of the upper decks to wreck-specialty and technical-penetration divers, and it is the natural first Bass Strait dive before the Graveyard.

Boat only. Charters run from Queenscliff Harbour – about 25 minutes by boat – and from Portsea Pier (35–45 minutes through The Rip): Dive Victoria Group, Red Boats, Bay City Charters and Chimney Rock Charters all schedule it. Drive Melbourne–Queenscliff via the Geelong Ring Road and Bellarine Highway (1 h 40 min).

Private boats launch at Queenscliff or, when the bar is safe, the Barwon Heads river ramp (4 km), and must pre-book the public mooring No. 2 through Parks Victoria's Parkstay site ($30 per vessel for a 2-hour slot); anchoring on the wreck is prohibited and licensed operators use mooring No. 1. Both moorings are marked by special buoys at the bow end. Divers need to show an entry-level certification (AS4005.1) and are strongly advised to do an orientation dive with a guide first.

Sits in open Bass Strait 2.5 km off a surf beach, so swell is the issue: charters generally cancel above about 1.5–2 m of south-west swell, and even at 1 m the shallow superstructure (7–8 m at the bridge) is surgey – Diveline warns the site can be quite surgey and dangerous and should be dived only in favourable conditions. Light northerly winds give flat water and the best visibility (15–20 m in autumn); strong westerlies and south-westerlies close it. Tidal stream is slight here compared with The Heads and the wreck can be dived at any tide, but the passage from Portsea through The Rip is planned around slack.

Visibility drops after heavy rain when the Barwon River plume drifts east. Winter closures of a week or more are normal.

First dive: descend the mooring to the bridge roof (about 8 m), drop to the main deck and swim aft along the high (port) side past the funnel and hangar to the flight deck and stern (20 m), return along the starboard side at 24–28 m past the hull openings and up over the bow (15 m) to the mooring. Second dive: penetrate with a guide through the cut access holes into the bridge, captain's cabin, galley, mess decks and operations room, staying in the daylight zone. Safety stop on the mooring line or the mast at 5 m.

Recreational with extensive penetration; EAN32 recommended. Wreck-penetration courses and CCR training use the lower decks; run lines from the access holes. Parks Victoria entry-level certification requirement applies to all divers.

Dive Victoria Group (Queenscliff and Portsea) – daily double dives in season and most days year-round, plus night dives; Red Boats (Queenscliff) – several charters a week; Bay City Charters and Chimney Rock Charters (Queenscliff) – regular weekend and midweek trips; Bayplay (Portsea) and Diveline (Frankston) run Advanced and Wreck courses on it. The most-dived wreck in Victoria.