Jimmy's Cave is one of several dedicated cave and cavern features that make Seal Rocks' underwater topography distinctive among mid-north-coast dive sites, sitting at a genuinely deep 33 to 34 metres and requiring torches to appreciate fully. The cave's signature feature is a large inner chamber nicknamed 'the ballroom', spacious enough to hold a group of divers comfortably and typically filled with a dense, swirling mass of ladder-finned pomfret that gives the space a dramatic, almost theatrical quality when lit up by dive torches. Spider lobsters are a reliable find in the cave's crevices and ledges, adding a macro-interest layer to what is otherwise primarily a topography and fish-life dive.

Given its depth, Jimmy's Cave sits at the edge of standard recreational limits and inside an overhead environment, so it is recommended only for divers with cave or cavern training or, at minimum, very close supervision from an experienced local guide familiar with the cave's layout and any hazards. The site is usually dived alongside the neighbouring Interlinked Caves and Labyrinth system as part of a broader Seal Rocks cave-diving excursion, since all three sit in a similar area and depth range. This cluster of caves is a major reason Seal Rocks stands out from otherwise broadly similar mid-north-coast reef and pinnacle sites, offering genuine cavern topography rather than just open reef, and it rewards divers with the training and experience to explore it properly and safely.

Bring a reliable primary and backup light, since the ballroom's full effect and the spider lobsters in the surrounding cracks are easy to miss without good illumination at this depth.

Boats for the Seal Rocks sites either run the longer distance down from Forster/Tuncurry (about 45-60 minutes) or launch locally from the small boat ramp at Seal Rocks village itself, near Sugarloaf Point, cutting the run to Big and Little Seal Rock down to 10-20 minutes. Seal Rocks is a small, remote settlement reached via Lakes Way/Mungo Brush Road through Myall Lakes National Park; there is no dedicated dive shop in the village itself, so most Seal Rocks charter diving is booked through Forster Dive Centre, with divers sometimes meeting the boat locally rather than travelling from Forster.

Seal Rocks sits on an exposed headland with Sugarloaf Point taking the full force of easterly and south-easterly swell — trips are cancelled in anything beyond about 1.5 m swell, and the site is often diveable when more sheltered locations further north are blown out, or vice versa, so conditions should always be checked specifically for Seal Rocks rather than assumed from Forster. Visibility is typically 15-30 m and can be excellent in settled autumn and winter weather; it drops after the Myall Lakes and Wallis Lake systems discharge following heavy rain. Grey nurse sharks are present at almost any time of year here, with numbers varying seasonally, and the wrecks (Satara, Catterthun) require calm, low-current conditions for safe deep/technical diving.

Descend to the cave entrance at around 33 m with torches on, enter carefully to avoid disturbing the substrate, and make for the ballroom chamber where ladder-finned pomfret gather in numbers; check crevices along the way for spider lobsters, then retrace the route out the same entrance.

Recommended for cave/cavern-certified divers or under close guide supervision; deep dive at the edge of recreational limits — plan gas and no-decompression time conservatively.

Forster Dive Centre (Tuncurry) — regular boat trips to Seal Rocks, year-round, weather permitting.