The Glenelg Barge was the first of Adelaide's purpose-sunk wrecks, scuttled in 1984 a short distance from where the Dredge would follow a year later. She is a sand hopper barge about 30 m long, built in Sydney in 1911 by Poole and Steel, with a capacity of around 450 cubic yards, and spent her working life in state service carrying dredged spoil. Today she rests on the sand in about 20 m, a boxy, flat-topped hull that is simpler in shape than the Dredge but just as encrusted.

Because the barge is essentially a large open-topped box with buoyancy chambers down each side, the character of the dive is different from its neighbour. The outside of the hull is covered in sponges, ascidians and bryozoans, and schools of bullseyes, old wives and sweep drift along the sides. Leatherjackets, magpie perch and blue devils are common, and nudibranchs are a highlight for photographers who slow down on the hull plates.

There are fewer fish than on the Dredge, but plenty of life overall. Small work rooms on the barge can be looked into, but the flotation chambers have very restricted entrances and have silted up; local guides advise against entering them. The best way to enjoy the Barge is as part of a two-wreck dive, linked to the Dredge by a line of star droppers on the seabed, which also makes for good navigation practice.

With both wrecks so close, it is one of the few places near Adelaide where a diver can see two quite different steel vessels in one tank. The Barge suits Advanced divers comfortable with open-water boat diving and variable visibility, and it is a good site for developing wreck awareness without committing to penetration. For history buffs, it marks the start of the 1980s artificial-reef program that shaped Adelaide's offshore diving.

Boat access only. Adelaide Scuba runs its charters from its shop on the Patawalonga at Glenelg North, with the boat leaving through the Patawalonga/Holdfast Shores entrance; private boats launch at the West Beach boat ramp (Barcoo Road end of the West Beach dunes, large trailer park, fee payable) or the Glenelg (Holdfast Shores) ramp. From Glenelg it is a run of about 10-20 minutes due west in flat water.

Use GPS marks: the sites are low-relief and cannot be seen from the surface, and there are no public moorings, so anchor in sand off the structure and leave a boat attendant with a dive flag up because charter and fishing traffic is steady on weekends. The Barge is usually dived as the second half of a Dredge dive, following the star-dropper trail between the two.

The metro coast faces west into Gulf St Vincent, so the rule is simple: offshore easterly winds flatten the sea and clear the water, while westerlies and south-westerlies build a short, steep chop and stir up the silty bottom. In summer the south-westerly sea breeze usually arrives by late morning or early afternoon, so boats aim to be back in by lunchtime. Northerlies are workable when light.

The gulf has a mixed, small-range tide with 'dodge tides' (neap periods when the water barely moves) that give the easiest diving; strong spring tides can run noticeably across the offshore wrecks. Visibility drops for several days after strong westerly blows and after heavy rain when stormwater and Patawalonga/Torrens outflow reach the coast.

Most divers start on the Dredge and swim the star-dropper trail south to the Barge when the current is light, then return to the anchor. If diving the Barge alone, drop on the sand beside the hull at 20 m, swim a full lap at the base, then a second lap over the deck edge at about 16-17 m looking into the small work rooms from outside. Keep an eye on air: the transfer between wrecks eats time.

Safety stop on the anchor line.

Air or EANx 32. Interior spaces are silted and restricted – not a penetration dive.

Adelaide Scuba (Glenelg North) – combined 'Dredge and Barge' boat trips; Underwater Sports and The Dive Shack – occasional club boat dives; private boats from West Beach.