The Jew Grounds are a deep reef south of the ex-HMAS Adelaide, and the name - an old fishing term for the mulloway (jewfish) that frequent deep reefs along the NSW coast - tells you why the spot was known long before divers visited. The Terrigal Underwater Group lists it at 36 m, noting nice fixed growth and fish life. At this depth the reef is dominated by fixed invertebrates rather than algae.

Sponges in many shapes and colours, sea whips, gorgonian fans, ascidians and bryozoans cover the rock, and the low light gives the reef a muted, deep-water look that brightens under a torch. Ledges and overhangs shelter bullseyes and cardinalfish, and big fish are the reason fishers valued the spot: mulloway, snapper and kingfish may be seen, along with red morwong, Maori wrasse and wobbegongs. Schooling yellowtail and silver sweep hang above the reef.

Being so close to the Adelaide, the Jew Grounds show what the seabed in this area looked like before the frigate became the main attraction, and they give experienced local divers an uncrowded deep reef a few minutes from the ramp. Published detail on the layout is scarce, so dives tend to be short explorations close to the anchor. With depths to 36 m, no-decompression time on air is short, narcosis is noticeable, and gas planning matters.

This is a site for Deep-certified divers with recent experience, ideally using nitrox at an appropriate mix or diving to a planned decompression profile with suitable training. It suits divers who want a quiet, deep reef with good fixed growth and a chance of big fish.

All boat dives in this area launch from the Terrigal Haven boat ramp at the southern end of Terrigal Beach, tucked behind The Skillion headland. From the Central Coast Highway follow Terrigal Drive into Terrigal, then Kurrawyba Avenue and Terrigal Esplanade to The Haven, where there is a paid car park beside the ramp; Pro Dive Central Coast's shop is a short walk away and gear is loaded on the ramp or the adjacent beach. Private boats need a ramp with good parking early on weekends as the car park fills by mid-morning in summer.

The Jew Grounds lie south of the ex-HMAS Adelaide off Avoca/North Avoca, only a few minutes further than the Adelaide from The Haven (about 5-10 minutes). Unlike the Adelaide there are no public moorings, so boats anchor with GPS and sounder.

Terrigal's offshore reefs are open to the Tasman Sea and are dived only when swell is below roughly 1.5 m; a north-east sea breeze building through the afternoon in summer and strong southerlies after a front are the usual reasons trips are cancelled, so morning departures are the norm. The Haven boat ramp is sheltered by The Skillion but the run out past the headland can be lumpy in a south-easterly. Visibility is best in late summer and autumn when the East Australian Current pushes warm blue water inshore, and worst after heavy rain when Terrigal Lagoon, Wamberal Lagoon and Avoca Lagoon open and stain the inshore water.

Winter water is cooler (around 15-17 °C) but often clear. Deeper offshore reefs also need manageable current - when the East Australian Current runs hard, skippers may skip them for sites closer in.

Descend the line directly to the reef at 32-36 m, explore a limited area close to the anchor with an early turn, and begin the ascent while within no-deco limits or as planned for staged decompression. Safety stop at 5 m for at least 3-5 minutes.

Deep dive: EAN25-28 or air within limits; consider staged decompression training; carry redundant gas (pony) for solo/team safety.

No regular scheduled trips; dived by Terrigal Underwater Group and experienced private boat groups, and occasionally by Pro Dive Central Coast for deep-qualified divers.