The Tuggerah is Sydney's most dived technical wreck and, by common consent, its fishiest. Built by Clyde Shipbuilding in Scotland and launched on 31 August 1912, she was a 56 m, 749-ton steam collier with a 927 hp triple-expansion engine and two Scotch boilers, working coal from the Illawarra to Sydney. On 17 May 1919, having loaded at Bulli jetty in rough weather with the cargo not properly trimmed, her master chose to sail rather than wait; off Marley Beach a six-metre wave struck her port side, the coal shifted, and she rolled and sank within minutes.

Six men died, including Captain McConachie; eleven survived after hours in the water. Coming six weeks after the Myola, the loss hastened reforms to collier loading practice. She lies on her port side on sand at 45–49 m.

The bow has collapsed, but from the boilers aft the ship is remarkably complete: divers pass between the boilers and the hull plating into the engine room where the three cylinders and their con-rods stand as they were, visit the workshop, and follow the hull to the propeller and rudder at the deepest point under the stern. A thick trawl rope now lies across the boilers, apparently from a 2024 trawler snag, and the wreck continues to deteriorate under the heavy seas of this open stretch. The marine life is what brings people back.

The hull is enveloped in bullseyes, nannygai and yellowtail so dense that the structure disappears inside the school; wobbegongs occupy every crevice; grey nurse sharks, Port Jackson sharks in extraordinary numbers (120 counted in one dive), giant cuttlefish, serpent eels, numbrays and stargazers are all recorded, and Australian fur seals frequently drop in. Visibility is usually better than 15 m.

Boat only, 2.2 km off Marley Beach, roughly 8 km south of the Port Hacking entrance. Technical charters leave from Cronulla public wharf or the Port Hacking ramps (Gunnamatta Bay, Lilli Pilli), 25–35 minutes; Sydney Dive Charters also runs here from Cronulla or Rose Bay on request. The wreck rises several metres off the sand and is an easy sounder target, but strong northerly surface current is common and the shot must be placed on the boilers.

Drifting decompression with a following boat is the norm.

Exposed to all swell directions; dived in under 1.5 m seas. The defining hazard is current, usually setting north and mostly in the surface layers, strong enough to sweep divers off the shot; dives are aborted if the shot line is streaming hard. Surface conditions can look poor while the bottom is clear, and visibility ranges from 3 m to over 40 m, typically better than 15 m.

Winter gives the clearest water; run-off from Port Hacking after rain affects the inshore layer only.

Descend the shot to the boilers at about 44 m. Swim between the boilers and the hull into the engine room to see the triple-expansion cylinders and con-rods, visit the workshop space, then follow the more intact stern to the propeller at 48–49 m before returning forward along the collapsed bow section. Fifteen to twenty minutes, then staged decompression on a drifting station, with about 20 minutes of stops on air tables.

Trimix 18/45 or 21/35 typical; 15–20 minutes bottom time with 50%/100% deco gases; CCR friendly. Reel for engine-room penetration. Sydney Dive Charters requires Tec 40/T1 and 100 logged dives.

Sydney Dive Charters – Tec 1 charters (Thursday/Sunday programme, Cronulla or Rose Bay departures); Abyss Scuba Diving, Frog Dive and Pro Dive Cronulla run technical trips several times a year; the busiest technical wreck in Sydney.