The Aldinga Pinnacles are the gentler partner to the Drop-off, a cluster of about ten rock pinnacles closer inshore within the Aldinga Reef Sanctuary Zone. The Marine Life Network describes them rising from around 20 m to about 5 m, while the Federation and the Dive Shack give a typical depth of about 8 m on the reef around them. On clear days they can be seen from the surface.

The pinnacles are sculpted limestone with swim-throughs, overhangs and ledges, and they are covered in weed growth on top and sponges, soft corals and ascidians on the shaded sides. The Marine Life Network describes a staggering amount of fish – blue devils, bullseyes, boarfish and old wives – and plenty of nudibranchs for macro photographers, calling the site a photographer's paradise. Because the reef is unfished, the fish are relaxed around divers.

The area is also considered a snapper breeding ground. The Dive Shack recommends around 60 minutes of bottom time and notes that visibility is generally very good. With the tops in 5-8 m and the most interesting structure in 8-12 m, the Pinnacles make a long, relaxed dive, ideal as the second dive after the Drop-off or as a first Aldinga dive for Open Water divers.

The same caution applies as at the Drop-off: local sources advise against diving the offshore reef when snapper are running because white sharks sometimes follow them. Outside those periods, the Pinnacles are one of the most rewarding reef dives in the Adelaide region.

Boat access. Most divers launch at O'Sullivan Beach boat ramp and run south about 15 km along the coast (roughly 25-40 minutes depending on the boat); small boats can also be launched from the beach at southern Aldinga Beach where vehicle beach access is permitted. The reef lies inside the Aldinga Reef Sanctuary Zone off Snapper Point, about 1-1.5 km offshore.

There are no public moorings; anchor in sand clear of the reef and leave an attendant aboard with a dive flag. On clear days the pinnacles can be seen from the surface.

Aldinga faces west into Gulf St Vincent. The best days follow several days of offshore easterly winds, when the sea is flat and visibility can exceed 15 m; westerly and south-westerly winds and swell quickly make it rough and stir the silt in the deeper areas. The summer sea breeze from the south-west usually arrives late morning.

Local guides mention strong currents at times from upwelling along the drop-off, so neap dodge-tide days are easiest. Autumn (March-May) is often the most reliable period. Local advice is not to dive the offshore reef when snapper are schooling (typically late spring-summer), as white sharks sometimes follow the schools.

Anchor on sand between pinnacles, then weave from one pinnacle to the next at 8-12 m, exploring swim-throughs and overhangs, spiralling up each pinnacle before moving on. Keep a compass bearing to the anchor; finish on a pinnacle top at 5 m for the safety stop.

Occasional shop and club boat trips from O'Sullivan Beach, usually paired with the Drop-off; frequently visited by private boats.