The Limestones is a distinctive geological feature among Newcastle's offshore reef dives: a jagged, sharply layered outcrop that rises abruptly from the surrounding sand at 23 m up to around 13 m, its stepped strata giving it a very different character from the smoother sandstone reefs elsewhere along this coast. Local divers speculate the formation may be the remains of an ancient fossil coral reef, and whether or not that origin story holds up geologically, the outcrop's sharp-edged, tiered structure certainly stands out from the more typical bare rock and boulder reefs nearby. It sits near the historic Irresistible wreck ground, adding a bit of maritime-history interest to what is primarily a scenic reef dive.The layered ledges created by the outcrop's structure provide countless small shelters, and reef fish make full use of them — the site is known as a good spot for finding fish tucked into the numerous crevices and overhangs rather than seeing large numbers in open water.

It's a comfortable depth range for Open Water-certified divers with some experience, sitting shallower than North Reef and Big Ben, and its varied, tiered profile rewards a slow, methodical exploration rather than a fast swim-through. As with the rest of Newcastle's offshore reefs, visibility and fish activity both improve markedly when the East Australian Current is pushing warm water down the coast, and the site is typically dived as part of a multi-reef charter day out of Newcastle Harbour. Photographers in particular favour The Limestones for the way the light rakes across the tiered ledges in the middle of the day, picking out the sponge and algae growth colonising each layer, and the site's moderate depth range makes it easy to combine with a deeper dive on North Reef or Big Ben earlier in the day without pushing no-decompression limits too hard.

Launch from Newcastle Harbour and run a short distance offshore near the Irresistible wreck ground; booked through Dive Newcastle or reached by private boat.

These are ocean shore dives fully exposed to Pacific swell, so a flat or near-flat sea and low easterly swell are essential — anything over about 1 m makes entry and exit across the rock platforms hazardous. Best conditions come after several calm days with a light westerly or northerly breeze; a building south-easterly or nor'easter blows the sites out quickly. The East Australian Current periodically pushes warm, clearer tropical-influenced water down this coast in late summer and autumn, lifting both visibility and the variety of fish life; a southerly current reversal brings cooler, greener water.

Visibility drops for several days after heavy rain due to river and stormwater runoff from the Hunter River and city catchments.

Descend to the base of the outcrop at 23 m, work up through the jagged layered ledges to about 13 m, checking the shaded ledges for reef fish, before ascending for a safety stop.

Dive Newcastle includes The Limestones on its rotating offshore reef charter schedule.