Southern Wall is one of the many named dive sites on Bougainville Reef, the small, isolated Coral Sea reef about 230 km north-east of Cairns and 150 km south of Osprey. It is known only from a list of possible Bougainville sites on Dive the World, and no description of its layout, depth or highlights was found in the sources consulted. The name indicates a wall on the southern side of the reef, which would be exposed to the prevailing south-east trades and so dived only in lighter winds; that is an inference from the name and the reef's orientation.

Bougainville rises from deep water, and almost every site on it combines a shallow reef top with a wall or steep slope that falls hundreds of metres. The reef's other documented sites give a sense of what to expect: The Zoo and Corner Shop are walls with grey reef, whitetip and blacktip sharks, turtles and schools of butterflyfish, unicornfish and snapper; Walmart has a wall crowded with basslets and invertebrates; Crystal Plateau is a hard-coral terrace with giant potato cod; and Dungeons & Dragons is a maze of reef-top caves. Visibility of 20–40 m is typical, and currents are usually mild but can pick up on the corners.

Bougainville usually gets one day on a Mike Ball Coral Sea itinerary, and the crew picks three or four dives from a long list of named sites depending on wind, swell and current. This record is provisional and should be expanded when an operator description becomes available. Divers who find it on their dive plan should ask the crew for the depth profile and highlights, treat it as a wall dive in blue water with the usual attention to depth, and log what they see so that the entry can be improved.

Liveaboard only. Mike Ball's Spoilsport visits Bougainville on its 4-night Osprey fly-dive (Cairns departure Thursday evening, return by flight from Lizard Island), 5-night Coral Sea & Cod Hole and 7-night Coral Sea expeditions; the overnight run from Cairns is roughly 230 km of open ocean. Bougainville is not guaranteed on every itinerary and is usually allocated one day.

Southern Wall is one of the lesser-used Bougainville sites and is dived from a mooring or tender drop at the crew's discretion.

Bougainville is a small, isolated Coral Sea reef about 230 km north-east of Cairns and 150 km south of Osprey, with no land to shelter behind, so the surface can be choppy in any SE trade wind over about 20 knots, common June to August. Conditions broadly follow Osprey's, though Bougainville is sometimes calmer when Osprey is windy. Currents are generally mild but can pick up on the corners and walls.

September to December usually gives the calmest seas and best visibility (20–40 m); December to April is cyclone season.

No published dive plan. Expect a Bougainville wall or slope dive: descend to the depth set in the briefing, follow the reef with the wall on one side, turn at half gas and ascend along the reef for a safety stop on the top.

Coral Sea liveaboards visiting Bougainville (Mike Ball Dive Expeditions) – occasional, crew's choice.