The Currajong is the best wreck in Sydney Harbour and the hardest to dive legally. She was launched in Glasgow in 1875 as the TSS The Clarence, a 67.6 m, 603-ton twin-screw passenger and cargo steamer for the NSW north-coast trade, renamed Currajong in 1883 and later converted to a collier carrying coal from the Illawarra. On the night of 4 March 1910, outward bound in ballast, she crossed the path of the AUSN liner Wyreema off Bradleys Head and was struck on the port side; she sank in minutes in the main channel and one man died.

Too deep to be a hazard to shipping of the day and too expensive to raise, she was left, and she lies today exactly where she fell, in the busiest stretch of water in Australia. The hull is almost completely intact and upright with the bow pointing toward Bradleys Head, deck at 18 m at the bow and 22 m at the stern, sand at 23–27 m. Two open holds, the donkey boiler, winches, the poop deck and steering gear are all there, and on the port side the plating is folded in where the Wyreema's bow entered.

The interior is floored with a century of dead oyster shell; limited penetration is possible but rarely worth the silt. Schools of jewfish, bream, luderick, yellowtail and one-spot pullers crowd the stern and poop, and decorator crabs cover the rails, which is why the charter markets it as a photography dive. The restrictions are absolute: the wreck is in the shipping channel, so it is dived only at slack high water after midnight under Port Authority conditions, ascending on a line.

Shore divers have reached it from the Bradleys Head steps along a staked route, but ferries pass overhead at full speed and the practice is neither safe nor clearly lawful. It suits Advanced divers who join the monthly charter and accept a 1 am start for the privilege of seeing a 1910 collier that almost nobody has.

The wreck lies in the harbour's main shipping channel 230 m south-east of the Bradleys Head mast, GPS 33°51.31'S 151°14.94'E (WGS84). Sydney Dive Charters runs it as a monthly night dive (first Friday), departing Little Manly ramp or Rose Bay wharf at about 1 am so as to be on the wreck at slack high water when harbour traffic is minimal, under arrangements with the Port Authority; Advanced certification and 20 logged dives required. Shore divers have reached it from the steps below the Bradleys Head mast, swimming out at depth on a 120° bearing along a line of stakes (scooters help), but the legality of doing so in the channel is uncertain and the traffic hazard is severe.

Exit is back at the steps or the boat.

The Currajong is dived only at slack high water, when the flood has brought clean water up the harbour and the tidal stream in the channel has stopped, and only at night when ferries and shipping are at a minimum – the charter departs around 1 am. Visibility ranges from centimetres to 10 m and is destroyed by rain for days. Weather is irrelevant beyond wind chop; traffic is everything.

Daylight diving in the channel is effectively prohibited.

Descend the shot to the deck at 18–20 m near the bow, which points toward Bradleys Head. Swim aft along the deck past the two holds, the donkey boiler and winches to the poop deck and stern at 22 m, look at the great indentation on the port side where the Wyreema struck, peer into the holds (limited penetration only), and return to the shot. Ascend strictly on the line; no free ascents in the channel.

Night, low-visibility and navigation experience essential; strobe on the shot line; no free ascents.

Sydney Dive Charters – monthly night boat dive (first Friday of the month, 1 am departure, 2 hours, Advanced + 20 dives, peak high tide only); no other operator. Independent shore dives have been done from Bradleys Head but are not recommended.