The northern breakwall at Stockton is built on shipwrecks. The Oyster Bank off the Newcastle Harbour entrance was among the most dangerous places on the Australian coast in the age of sail and steam, and when the breakwall was extended across it, the remains of ships lost on the bank were incorporated into or buried alongside the wall. Grey Nurse Charters lists PS Cawarra (12 July 1866), SS Colonist (9 September 1894), SS Wendouree (20 July 1898), SS Lindus (4 June 1899), the French barque Adolphe (1904) and Regent Murray (7 April 1898, visible on both sides of the wall), and notes that two vessels, the Elamang and the Katoomba, were deliberately grounded as foundations for the wall.

The Cawarra is the most tragic: a paddle steamer that went down attempting to enter the harbour in a storm, with 60 deaths - still one of Australia's worst peacetime maritime disasters, with only one survivor. The Adolphe, whose bow still rises above the breakwall, is described separately. Underwater, the site is a confusing jumble.

Grey Nurse Charters describes piled wrecks creating confusing dive conditions in up to about 8 m, where iron plates, frames, boilers and fittings are mixed with breakwall boulders. Poor visibility is common, since the Hunter River flows out right beside the wall. Luderick, bream, mullet, leatherjackets and small reef fish shelter among the structure, and blennies and crabs occupy the gaps.

This is a dive for history enthusiasts willing to accept low visibility and complicated access. Diving with someone who knows the site - Grey Nurse Charters or local divers - is strongly recommended, as is timing for high tide after a dry spell.

From Newcastle cross to Stockton by the Stockton ferry (Queens Wharf) or by road over the Stockton Bridge, and park near the southern end of Stockton at the base of the northern breakwall (Pitt Street/Mitchell Street area). Shore divers face a long walk with gear along the breakwall; Grey Nurse Charters describes the site as a boat dive or shore dive after a long walk. Boat divers run a few minutes from the Newcastle ramps but must stay clear of the shipping channel.

The breakwall is at the mouth of the Hunter River, so tide and rainfall control the dive: visibility is poor on the ebb and after rain, and best at high tide after a dry spell. The seaward side is exposed to easterly and southerly swell, which breaks on the Oyster Bank, so dive only in small seas (under about 1 m). Strong tidal flow runs along the harbour side of the wall; plan for slack water.

With a guide, enter near the known wreck sections and move slowly along the base of the wall, identifying plates, frames and machinery among the rocks. Keep shallow and close to the wall, surface only near the wall, and never stray into the shipping channel.

Protected historic shipwrecks under the NSW Heritage Act; port regulations apply near the harbour entrance.

Grey Nurse Charters dives the Newcastle wrecks and reefs by arrangement from Newcastle Harbour and Swansea; Dive Newcastle and local clubs dive them from private boats. There is no fixed daily schedule - trips run on demand and conditions.