Elbow Cave sits on the western side of the southern part of North Solitary Island, where a reef fans out from the island in a broad semi-circle for 75 to 100 m, cut by a series of gullies running roughly north-south across the reef top. The cave itself is a small, uncomplicated swim-through best entered from its southern side, delivering divers into the main gully system at around 12 to 13 m — an easy, non-technical overhead section rather than a demanding cave dive, which keeps the site accessible to Open Water divers. The site's real drawcard is the sheer volume of life packed into a shallow, sheltered setting: tens of thousands of anemones carpet the reef, hosting several clownfish species side by side — Clark's, red, false clown, three-spot dascyllus and orange anemonefish have all been recorded here — alongside guineafowl moray eels, a good range of nudibranchs, Spanish dancers and egg cowries.

Scattered through the site, now so heavily encrusted with coral and sponge growth that identification is difficult without local knowledge, are the remains of a fishing trawler that sank here around 1988 or 1989, adding a modest wreck element to what is otherwise a pure reef dive. Concrete plaques installed some years ago by the NSW Marine Parks Authority as part of an interpretive underwater trail can still be found around the site, though their upkeep has not kept pace with the growth covering them. What sets Elbow Cave apart from many Solitary Islands sites is the sheer amount of time divers can comfortably spend there: with depths rarely exceeding 13 m and typically excellent visibility of 20 to 30 m, dives here regularly run 75 to 80 minutes, far longer than the 30-40 minute dives typical of the deeper sites at South Solitary Island or Pimpernel Rock.

Combined with calm, current-free conditions in the lee of the island, this makes Elbow Cave one of the best sites in the whole marine park for unhurried macro photography, and it is accessible only through Wooli Dive Centre, which requires a minimum group of six to run the trip.

Wooli Dive Centre is the only operator serving this section of coast and departs from the Wooli River wharf in the small village of Wooli, reached via Wooli Way off the Pacific Highway/Grafton-Wooli Road. The river mouth has a shallow, shifting bar that the operator's purpose-built jet-propulsion vessel (able to run in very shallow water) is specifically equipped to cross; private trailer boats should not attempt this bar without strong local knowledge. From the wharf it is roughly 25 minutes to North Solitary Island's southern sites and up to 90 minutes to Pimpernel Rock in the north of the marine park, weather dependent.

Wooli Dive Centre requires a minimum group size (around six divers) to run a charter to the more remote sites. Elbow Cave requires a minimum group of six divers to be included on a Wooli Dive Centre charter.

North Solitary Island and Pimpernel Rock sit fully in the open ocean north of the more sheltered Coffs Harbour grounds, so trips depend on a genuinely settled weather window — under about 1.5 m swell and light-to-moderate winds — and are cancelled more often than the South Solitary Island trips run from Coffs. The Wooli River bar itself is shallow and can be dangerous in a big swell or a strong outgoing tide; the dive centre's shallow-draft, high-powered vessel is built specifically to manage it, but the bar can still close the operation down on a bad day. Visibility offshore is normally excellent, in the order of 15-30 m, but summer brings warmer water (up to 25°C) with more current from the East Australian Current, while winter is cooler (down to about 18-19°C) but often calmer.

Cyclone-influenced swells from the Coral Sea can affect this coast in late summer/early autumn even without a direct cyclone hit.

Descend onto the reef top at about 6 m, follow the north-south gullies to the swim-through, entering Elbow Cave from the southern side and emerging into the main gully system at 12-13 m, then spend the remainder of the long available bottom time working the anemone beds and trawler wreckage before an unhurried ascent.

Only accessible through Wooli Dive Centre, and only run with a minimum group size of about six divers.