The Boulders occupies the eastern flank of the northern part of North Solitary Island, where enormous boulders and a series of deep gullies create some of the most dramatic large-scale topography anywhere in the Solitary Islands Marine Park. Depths start around 20 m close in against the island and increase quickly to 25-30 m or more moving east, and the standout feature is a channel running between the island's two sections that local divers have nicknamed the Grand Canyon for the scale of the boulder walls rising either side of the swim. This scale attracts correspondingly large marine life: grey nurse sharks use the gullies and cave mouths as resting spots, Queensland groper of well over two metres have been recorded emerging from caves here, and huge rays, eagle rays and big schools of kingfish and yellowtail work the current lines between the boulders, alongside firefish and bream in the more sheltered pockets.

This is unmistakably a site for experienced divers: there is no permanent mooring, so the boat must track divers' bubbles and wait for them to surface, entries are typically negative or fast to beat any current, and the depths involved put much of the site's best features at or beyond recreational no-decompression comfort margins for less experienced divers. Because of the depth, the lack of a mooring and the generally more exposed position on this side of the island, Wooli Dive Centre only runs The Boulders in calmer weather windows and, as with its other remote sites, requires a minimum group of six divers to justify the run. For divers with the certification and experience to handle 25-30 m depths and moderate current, though, this is regarded as one of the most impressive big-topography, big-animal dives in the entire Solitary Islands Marine Park, on a par with the more famous Manta Arch at South Solitary Island but with a fraction of the diver traffic.

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. The Boulders requires a minimum group of six divers and about 25 minutes' run from Wooli.

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 close to the island in the shallower 20 m section, work east into the deepening gullies and along the boulder-lined channel between the island's two sections, watching for grey nurse sharks and large groper in the cave mouths, and turn well before reaching decompression limits given the 25-30 m depths.

Only accessible through Wooli Dive Centre with a minimum group of six divers; no permanent mooring so the boat drifts or waits above the group.