South West Solitary Island, more commonly known by its old nickname Groper Island, sits about 12 km north-east of Coffs Harbour, closer to the mainland than South Solitary Island proper, and is valued in the marine park for two related things: its extensive plate coral growth and its habit of turning up unusual fish species not commonly seen at the more famous sites nearby. With usable depths generally in the 10-16 m range and occasional deeper pockets to 18 m, it is also one of the shallowest and most forgiving of the group's islands, making it a good choice for long, relaxed dives and for snorkelling. Two moorings are typically maintained, both on the northern side of the island for shelter on days of southerly wind: the eastern mooring sits over large gravel-based gutters running into the island interspersed with rocky nooks, while the western mooring lies over a gently sloping bottom with particularly prolific coral cover, the most interesting sections of which are found in the shallows rather than at depth.

Egg cowry shells and nudibranchs are reported in good numbers, and the 'unusual fish' the site is known for reflects its position at the northern, warmer edge of the group where tropical vagrants pushed south on the East Australian Current sometimes settle. Visibility at South West Solitary Island can be reduced compared with the more exposed South Solitary Island further offshore, given its closer inshore position, but this is a reasonable trade-off for a site that offers good shelter, gentle depths and consistently interesting coral cover. It functions well both as a primary destination on a quieter day and as a second, easier dive after a more demanding morning at South Solitary Island or the outer reefs.

Jetty Dive Centre departs from the public floating pontoon wharf in Coffs Harbour boat harbour, opposite the Attitude Burgers building (check in at 398 Harbour Drive). Private boats use the public ramp inside the harbour breakwall. South West Solitary Island (Groper Island) lies about 12 km north-east of Coffs Harbour, roughly 25 minutes by RIB.

Conditions off Coffs Harbour depend heavily on which island is being run: North West Solitary and Split Solitary sit closer inshore and are usable in more marginal weather, while South Solitary and any northern sites need a bigger settled window. Visibility across the group is generally 8-25 m and best away from river influence; the Coffs, Bellinger, Nambucca and Clarence systems all periodically dirty inshore water for a few days after heavy rain. Summer (Nov-Apr) is warmest with tropical vagrants and mantas; winter (May-Oct) is cooler with grey nurse sharks and giant cuttlefish.

Humpback whales pass April-November. Its two moorings, usually on the northern side, are specifically positioned to give shelter on a day of southerly winds.

Choose the eastern mooring for gravel gutters or the western mooring for coral-covered slopes depending on the day's plan, work the shallows at 10-12 m looking for egg cowries and unusual reef fish, and finish with an extended, unhurried ascent given the modest depth.

Jetty Dive Centre includes South West Solitary Island as a shallower, protected option, particularly useful on days of southerly wind.