The Noarlunga Tyre Reef is the original structure of the Noarlunga artificial reef, a field of tyre pyramids spread over a wide area of sand in 18-20 m off Port Noarlunga. It was built as a fish breeding reef and later became the site for the HA Lumb (1994) and the MV Seawolf (2002), which now sit alongside and partly within it. The pyramids provide shelter on a featureless silty seabed, and the Federation, Dive Shack and Marine Life Network all describe abundant fish.

Boarfish, cowfish, cuttlefish, octopus, blue devils, morwong, bullseyes, perch and wobbegongs are listed, and small fish crowd around the modules. The tyres carry sponges and small invertebrates. No particular hazards are listed, and local guides call it a pleasant dive.

The Marine Life Network warns that the pyramids are visually similar and it is easy to become disoriented, so compass navigation is important, especially in low visibility. Most divers use the reef as the third element of a dive on the two wrecks, or as a relaxed second dive at a similar depth. The tyre reef suits Open Water divers comfortable at 18-20 m and those practising navigation, and it offers a good chance of wobbegongs and cephalopods.

It is also an interesting example of the tyre-reef era of artificial reef building in South Australia, which began off Glenelg in the 1970s. The site's proximity to O'Sullivan Beach makes it an easy half-day outing. A torch helps to look into the dark centres of the pyramids, where octopus and small crayfish often hide.

Boat access only. Launch at the O'Sullivan Beach boat ramp (off Galloway Road; large trailer park, toilets) and run about 5 minutes south to the Noarlunga artificial reef, roughly 2.5-3 km west of Port Noarlunga jetty. The HA Lumb, MV Seawolf and Noarlunga Tyre Reef lie together, so one anchor or shot can serve all three.

There are no public moorings; anchor in sand beside the wrecks, not on them, and leave a boat attendant with a dive flag. Operators from Adelaide sometimes run here from Glenelg on days when Holdfast Bay is poor.

The Noarlunga artificial reef sits in open gulf water off the southern metro coast. It is diveable in light winds, ideally easterlies or light northerlies; westerly and south-westerly winds build steep chop quickly and the summer sea breeze usually arrives late morning to early afternoon. Tidal currents are usually mild but noticeable on spring tides – neap dodge tides are best.

The seabed is fine silt, so visibility varies greatly: up to 15 m after calm weather, but much less after westerly blows, after rain (Onkaparinga River plume) or when divers stir the bottom. Being close to O'Sullivan Beach, it is a good fallback when further sites are too rough.

Use the wrecks as the anchor point, then swim out among the pyramids on a compass bearing at 18 m, checking each module for wobbegongs, octopus and cuttlefish. Turn on a reciprocal bearing at half gas – the pyramids look alike.

Dived with the HA Lumb and Seawolf by club and shop boats (Sea Wolves, Underwater Sports, Adelaide Scuba) and private boats from O'Sullivan Beach.