JD Reef North is one of the NSW Department of Primary Industries' offshore artificial reefs, built for recreational fishing off Royal National Park. It lies about 900 m offshore and 540 m south-east of Barrens Hut, in 28–29 m of water. The reef consists of 18 concrete modules arranged in a Greek-cross pattern: four in the centre and three in each of the east–west arms, spaced roughly 50 m apart.

Each module is four metres square and five metres high and weighs 25 tonnes; ten of them carry steel pylons that extend their height to nine metres. The modules are hollow, and divers can swim right inside. Over the years they have sunk into the sand, and some have shifted: by 2024 one upper section had fallen and by February 2025 one of the four central modules had moved to rest against another.

The sand inside reaches almost 31 m. The early growth was only small barnacles, but by 2024–25 the concrete had gained small sponges and plenty of jewel anemones. Fish recorded include mado, yellowtail, boarfish, blind sharks, small rays and small flathead on the sand, with crayfish and crabs in the modules.

Visibility has ranged from poor to well over 15 m. The depth limits bottom time, and nitrox (EAN33) helps considerably. Because it was built for fishing, divers should avoid weekends, when fishing lines and anchors are likely.

It suits Advanced divers with deep experience who are interested in the colonisation of artificial reefs and in watching a new habitat develop over successive visits.

Boat only. Launch in Port Hacking (Gunnamatta Bay/Tonkin Park at Cronulla, Lilli Pilli or Bundeena ramps), run out through the entrance and turn right (south), passing between Jibbon Bombora and Jibbon Head in suitable weather, then follow the Royal National Park cliffs south. The reef is about 900 m offshore and 540 m south-east of Barrens Hut – 10 minutes from the entrance.

McFadyen's centre coordinates are 34° 05.659' S 151° 10.657' E. Drop a shot or anchor beside a module (not into it) in 28–29 m. Avoid weekends, when fishers crowd the reef.

The Royal National Park coast south of Jibbon faces east and takes swell from the north-east round to the south-east; southerly swell partly wraps around. These sites lie close to the cliffs, and the shallower ones need calm seas so that boats can anchor near shore and divers are not caught in surge – plan on seas under about 1–1.5 m. Westerly and north-westerly winds give the best conditions; a strong north-easter makes the return to Port Hacking rough.

Visibility is generally good because the coast is far from urban runoff, typically 12–20 m, occasionally 30 m. Being 900 m offshore, it is more exposed than the inshore Royal National Park sites and suits days with swell under 1.5 m. Visibility has varied from poor (February 2020) to well over 15 m (December 2024).

Current can run from the north.

Descend to a central module, look inside (the hollow modules can be entered), then visit the arm modules about 50 m apart along a compass bearing, returning to the shot. On EAN33, bottom time extends considerably; on air limit to about 15–20 minutes.

Nitrox EAN32–33 recommended.

No charter – private boats and St George Scuba Club. Built as a fishing reef, so heavily used by recreational fishers.