Merewether Reef — universally known to Newcastle divers as the Mowie Hole — is a rambling sandstone reef system a modest swim off Merewether Beach, one of the most popular ocean beaches in the city. Sitting in a comfortable 12-15 m, it's shallow enough for good bottom time and light penetration, but deep enough to feel like a proper reef dive rather than a beach paddle, and its position close to the Merewether Ocean Baths makes it one of the most accessible temperate reef dives on the NSW coast. The reef itself is broken sandstone rather than a single defined structure: low ledges, cracks, small overhangs and patches of open sand weave together over a reasonably large area, giving divers plenty to explore without a fixed route.The reef has built a strong reputation for macro photography, and the colourful sponge and soft coral growth on the ledges is a big part of the draw — reds, oranges and purples crust the rock in the shadier cracks, providing a colourful backdrop for red morwong, wobbegongs and spiny lobster tucked under the ledges.

Grey nurse sharks are also recorded here, using the reef as one of many aggregation points along this stretch of coast, particularly in the cooler months, so divers with an eye out and a bit of luck may share the reef with a shark quietly holding station over a gutter. Visibility swings with the East Australian Current: when warm water pushes down from the north in late summer and autumn it can turn beautifully clear and bring tropical stragglers with it, while a cooler southerly regime brings greener, planktonic water. Because it's an ocean-facing site with no real protection, sea state calls the shots — this is a fair-weather dive, but on the right day it's one of the better all-round reef dives within walking distance of a major regional city.

From central Newcastle, drive or walk to Merewether Beach and the Merewether Ocean Baths at the southern end. Park in the streets around the baths or at Burwood Beach car park. Entry is a rock-hop or swim out from the rocks beside the baths on a calm, low-swell day, heading out over the sand to the reef; exit the same way.

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.

Enter from the rocks by the baths on a calm day, swim out over sand to the reef edge, work the sandstone ledges and gutters looking into cracks for morwong, wobbegongs and lobster, then return along the same bearing to the entry point.

No dedicated boat charter to these shore sites; Dive Newcastle and local independent instructors run guided shore dives and Discover Scuba sessions here, and Newcastle-based clubs dive them regularly on weekends.