The Advance is a small, deep and relatively intact tug wreck off Catherine Hill Bay. COAST Magazine records her as a 180-ton iron screw steamer tug which, after surviving two earlier collisions, was lost in 1908; seven of her eight crew died. The Pro Dive network's site notes give the date as 25 December 1908 and the cause as a collision.

She lies about 5 km off Catherine Hill Bay and about 6 km south of Moon Island. What makes the Advance special is her condition. Pro Dive describes an upright tug sitting on sand in 43-46 m, with the boiler, the galley stove and intact side plating still in place.

Grey Nurse Charters, which lists her at 49 m, calls her relatively intact with a distinctive bow that has recently been damaged, but still clearly recognisable - an oasis of fish on the surrounding sand. For a wreck more than a century old in an exposed ocean location, that is unusual on the NSW coast, where most steamers of the era are reduced to machinery and ribs. Because she stands alone on sand, the wreck concentrates fish.

Grey Nurse Charters notes wobbegongs are particularly prevalent, and Pro Dive mentions nannygai; schools of yellowtail and bullseyes around the hull are typical of deep wrecks in this area. Sponges and small gorgonians grow on the plating. At 43-49 m, the dive requires decompression for any meaningful bottom time, and narcosis on air is severe.

It is suited to trained technical divers using trimix and decompression gases, who will find one of the most intact small wrecks between Newcastle and Sydney. The compact size means a single dive can cover the whole ship.

Boats launch from the public ramps inside Swansea Channel, either at Black Neds Bay beside the Swansea Bridge or at the Swansea/Lake Macquarie ramps, about 25 km south of Newcastle via the Pacific Highway. Parking with trailer bays is available at Black Neds Bay. The run is east along the channel, across the Swansea bar (check the bar and tide first - cross on the flood where possible) and a short distance out to the site; the Advance lies about 6 km south of Moon Island and about 5 km off Catherine Hill Bay - roughly 20 minutes from the Swansea ramps.

There is no published public mark; Grey Nurse Charters and Pro Dive run trips using their own GPS positions.

Moon Island and the reefs off Swansea Heads sit just outside the Swansea Channel bar, which is the deciding factor on most days: the bar is dangerous in any sizeable easterly or south-easterly swell and on a run-out tide, and Marine Rescue Lake Macquarie should be checked before crossing. Offshore, the sites prefer swell under about 1.5 m and light westerly or northerly winds; a strong nor'easter makes the eastern walls choppy, and a southerly swell pushes surge into the caves. Visibility runs 8-15 m and is best on a flooding tide, when clean ocean water replaces the lake outflow; after heavy rain the brown plume from Lake Macquarie can cover the inshore sites for days.

As a deep site well offshore, the Advance also needs light current and a stable forecast for the whole run time.

Descend the shot to the upright hull. Tour the bow (recently damaged), the side plating, the boiler and the galley stove, staying on the wreck. Return to the shot at the planned time and complete decompression on the line or a drifting SMB.

Trimix bottom gas recommended; EAN50/O2 decompression per team standards; redundant gas and SMB mandatory. Protected historic shipwreck.

Grey Nurse Charters (Swansea) runs trips on demand for qualified divers; the Pro Dive network lists it as an advanced/technical site; otherwise technical groups on private boats.