The Woniora is one of the deepest regularly identified wrecks off Sydney and a serious technical dive in the approaches to Port Botany. She was an iron collier built by Richardsons at Newcastle upon Tyne and launched in April 1863 – 42 m long, 6 m wide and 226 tons, with three holds, three masts for auxiliary sail and a rare 90 hp two-cylinder engine (one of only two such engines known on NSW wrecks) fed by a single coal-fired boiler. Owned in Sydney by Lloyd and Co. and later linked with the Bulli Coal Company, she carried Illawarra coal to Sydney.

On 28 October 1882 she left Bulli jetty with 242 tons of coal under Captain Henry Lauridson in heavy rain and a big easterly sea. About 9 pm, roughly three miles off Cape Solander, the cargo shifted to port, the ship took on a heavy list and suddenly rolled over and sank. Of the 15 to 17 aboard, only Heinrich Frederickson survived, drifting on an upturned lifeboat until he reached Kurnell beach at about 2 am.

The Marine Board found she had been overloaded and driven too hard for the weather. Fishermen knew the site for years and Max Gleeson heard of it in 1985; John Riley and Kevin Laybutt made the first dive in June 1987 and recovered the bell. The wreck lies roughly north–south, bow north, on sand at 63 m.

The main structure covers about 21 m: the engine stands upright at 59 m and the boiler rises to 58 m with the base of the funnel visible, while aft the stern post, rudder and a propeller with one blade exposed poke from the sand. The hull sides stand about a metre proud along the length, and forward an unidentified donkey boiler, a large winch and scattered items lie near the bow. Fish life is prolific, with dense schools of nannygai and yellowtail over the wreck.

Because of the depth, the currents and its position in the shipping channel, the Woniora is strictly for well-drilled trimix teams with full surface support.

Boat only. Launch in Botany Bay at Kyeemagh (Cooks River), Foreshore Road or Bonna Point, Kurnell, and run out through the heads; the wreck is just off the entrance, about 15–20 minutes from the ramps. McFadyen's GPS is 34° 01.1966' S 151° 15.6722' E; it gives a strong sounder mark and the old transit used Centrepoint Tower.

Because it lies in the shipping approach to Port Botany, divers must contact the Harbour Master (Port Authority of NSW) beforehand to find a 1.5–2 hour window with no ship movements and keep a surface watch and radio on channel 12/13. Drop a shot rather than anchoring.

Open-ocean site at the Botany Bay entrance, exposed to swell from the north-east round to the south; plan it only with seas under about 1.5 m and light winds, typically winter westerlies. Current is the main problem: the East Australian Current can run strongly from the north and tidal flow into and out of the bay sets across the site, so surface support must be able to follow drifting decompression. On the ebb, dirty bay water may reduce visibility near the surface.

The narrow window agreed with the Harbour Master around ship movements dictates dive timing more than the tide.

Shot the engine or boiler, descend on trimix, and survey from the boiler (58 m) and the upright engine (59 m) aft to the stern post, rudder and partly buried propeller, then forward along the hull sides to the donkey boiler, winch and bow. Keep bottom time around 20 minutes, then ascend the shot to a drifting deco station, with the boat tracking the team's SMB.

Trimix recommended (e.g. 18/35 or 15/50 back gas) with EAN50 and O2 for deco; typical 20 min bottom time gives 40–60 min of deco. Use a shot line and drifting deco station; rebreathers well suited. Contact Port Authority of NSW / Harbour Master for a shipping window.

Protected historic shipwreck.

No charter operator – technical diving teams on private boats only, with Port Authority/Harbour Master clearance for the shipping channel.