Archie's Cave is one of the less publicised sites in the South Solitary Island group, mentioned by Jetty Dive Centre alongside the nearby Steam Boiler as one of the 'other' local dive spots the operator will run when a group has already covered the marquee sites like Manta Arch and the Cleaner Station, or when conditions particularly suit a smaller cave/overhang feature over the more current-exposed moorings. Precise published detail on the site is thin — it does not feature in the same depth of description as Manta Arch or Buchanan's Wall — but it is understood to offer a small cave or overhang structure at a moderate depth typical of the island's general terrain. As with the other boulder and rock-mass sites around South Solitary Island, divers can expect resident wobbegong sharks tucked into the overhang, bullseyes and other schooling reef fish sheltering in the lee of the structure, and crayfish occupying the smaller crevices, along with the nudibranchs and encrusting invertebrate life typical of this part of the marine park.

The site's name suggests a local, possibly historical, association — likely named after a diver, fisherman or boat identified with the area — though the exact origin is not documented in available sources. Because Archie's Cave sees relatively little dedicated attention compared with the headline sites, it offers the appeal of a quieter dive within the same rich general ecosystem as the rest of South Solitary Island, without the crowds that can build around Manta Arch on a peak grey nurse shark season weekend. Divers particularly interested in this site should ask Jetty Dive Centre directly, since it is not run on a fixed schedule and its inclusion in a day's diving depends on group preference and conditions on the day.

Jetty Dive Centre departs from a public floating pontoon wharf on the Coffs Harbour boat harbour, opposite the Attitude Burgers building — check in first at 398 Harbour Drive, Coffs Harbour. It is roughly a 30-40 minute run out to South Solitary Island, 8 km offshore, in the dive centre's RIBs. Private boats launch at the Coffs Harbour public boat ramp inside the breakwall and follow the same course out past the harbour entrance.

South Solitary Island sits in open water 8 km off Coffs Harbour and is exposed to swell from the north-east through south-east; Jetty Dive Centre generally wants under about 1.5-2 m swell to run the outer moorings comfortably, switching to the more sheltered Split Solitary Island (only 20 minutes out) on rougher days. Visibility here is usually the best in the marine park given the distance from any river mouth, and the site's position at the boundary of tropical and temperate water means conditions can change quickly with wind shift. Summer (Nov-Apr) water is warmed by the East Australian Current to up to 26°C, bringing tropical fish, manta rays and, from December, leopard sharks; winter (May-Oct) cools to about 18°C but often gives calmer seas, giant cuttlefish and the peak grey nurse shark season (Jun-Nov, sometimes 30-60+ sharks on Manta Arch).

Humpback whales migrate past between April and November, peaking June-August northbound and September-November southbound. Currents can run strongly on the exposed north-eastern moorings (Manta Arch, Shark Gutters) and are much gentler on the sheltered north-western wall.

Descend to the cave/overhang area, explore carefully with a torch for crayfish and wobbegongs sheltering inside, and circle the surrounding reef before ascending.

Jetty Dive Centre (Coffs Harbour) runs South Solitary Island most days conditions allow, typically a double boat dive; it is the flagship site for the only major dive operator based in Coffs Harbour.