The Yongala is Australia's best-known wreck and routinely makes lists of the world's top ten dives, not because of its structure – though that is impressive – but because a 109 m steel hull sitting alone on a featureless sand plain has become an oasis for an extraordinary concentration of marine life. Built in 1903 by Armstrong Whitworth at Low Walker on the Tyne for the Adelaide Steamship Company, the 3,664-ton passenger and cargo steamer ran the Fremantle–Brisbane route and later the winter Melbourne–Cairns service. On 23 March 1911 she left Mackay for Townsville; the cyclone warning flags hoisted at Flat Top signal station went unseen, and she had no wireless.

She steamed into the cyclone and vanished with all 122 people aboard, along with a racehorse named Moonshine whose body later washed up at Gordon Creek. The wreck was located in the late 1950s by fisherman Bill Kirkpatrick and identified in 1961 when a safe recovered from it was traced by its maker, Chubb, to the Yongala's purser. Today the hull lies on its starboard side, listing 60–70 degrees, with the bow pointing roughly north and the upper (port) side at 14–16 m and the sand at about 28–30 m.

It is remarkably intact for its age: the bow and stern still rise off the bottom, masts, portholes and fittings are recognisable, and the whole structure is carpeted in hard and soft corals, sea whips and gorgonians. Everything above that is fish. Giant Queensland groupers drift along the hull, schools of trevally, barracuda, batfish and golden trevally circle overhead, huge marbled and bull rays rest on the sand and olive sea snakes forage in every crack.

Turtles sleep under the overhang and cleaning stations operate all along the upper hull. Bull sharks, tiger sharks and, in winter, minke and humpback whales are seen from time to time. Around 79 species have been recorded, with humphead Maori wrasse the most frequently logged.

The wreck is protected under the Commonwealth Underwater Cultural Heritage Act 2018, managed by the Museum of Tropical Queensland, with a 797 m protected zone. Penetration is prohibited and divers are asked not to let exhaled bubbles pool in the hull. It is a dive for Advanced divers comfortable with depth and current; for them it is one of the essential dives in the country.

Two ways in. The quickest is from Alva Beach, 15 km north-east of Ayr (about 1 hour 15 minutes' drive south of Townsville via the Bruce Highway, turning off at Ayr onto Alva Beach Road). Yongala Dive operates from its lodge at 56 Narrah Street, Alva, and launches its boat from the beach – divers carry kit only a short distance to the tractor-launched RIB – and the run to the wreck is about 30 minutes in good conditions.

From Townsville, Adrenalin Snorkel & Dive and other operators run full-day trips from Breakwater Marina (about 3–3.5 hours each way) or include the wreck on liveaboard itineraries. Private vessels need a permit from the Queensland Department of Environment and must use the public moorings; anchoring within the 797 m protected zone is prohibited.

The Yongala lies in open water with no lee at all, so it is the first site to blow out. Operators cancel if winds exceed about 20 knots, a strong wind warning is issued or swell is significant, and even moderate south-easterly trades make the ride and the surface interval choppy. Dives are timed for slack water around the top or bottom of the tide because tidal current across the wreck can be strong enough to sweep a diver off; on spring tides the usable window is short.

Visibility varies from under 10 m after south-easterly blows or Burdekin River flood plumes (wet season, January–April) to 25 m+ on calm neap days. Marine stinger season (box jellyfish and Irukandji) runs roughly November to May – wear a full-length stinger suit or wetsuit with hood and gloves, carry vinegar. Cyclone season November–April; tropical lows and cyclones can close sites and damage coral (TC Yasi 2011, TC Debbie 2017).

The best-odds months are August–November and the calm spells of the build-up.

Descend the tether to the wreck (arriving at the upper port side at 14–16 m), drop down to the sand on the first dive and work the deeper sections – bow, stern and the overhang where the hull meets the sand at 26–30 m – heading into any current first. Turn at 120 bar or with 10 minutes of NDL remaining, climb to the port rail and work back at 14–18 m past the cleaning stations. Return to your own line, do a safety stop on the line (3–5 minutes at 5 m).

The second dive stays shallower along the upper hull. Nitrox extends bottom time considerably.

Recreational no-stop dive; EANx 28–32% strongly recommended to extend bottom time at 20–28 m. Descent line mandatory. Penetration and bubble-trapping inside the hull are banned.

No technical diving permitted by operators.

Yongala Dive (Alva Beach) – two-dive day trips most days, weather and numbers permitting, 30 min run; Adrenalin Snorkel & Dive (Townsville) – scheduled full-day Yongala trips and liveaboard departures, ~3 h each way; Explore Whitsundays liveaboard (SV Summer Jo, 6 days from Airlie Beach) includes the wreck. Requirements: AOW (or in progress), 10+ logged dives, age 15+.