Cod Grounds is a Commonwealth marine park about 30 km south of Port Macquarie, sitting a few kilometres off Perpendicular Point at the mouth of Camden Haven, and it exists specifically to protect a small but critical piece of habitat for the east coast population of critically endangered grey nurse sharks. The seafloor here is not a single obvious feature but a scatter of rocky pinnacles rising off a sand and rubble bottom, ranging from about 18 metres on the shallowest peak down through sandy gutters, ledges and small caves to 46 metres at the deepest points within the four-square-kilometre park boundary. Those pinnacles and their surrounding structure support the crabs, lobsters, squid and reef fish that in turn sustain the sharks, and grey nurse sharks are recorded here year-round, with numbers building through the cooler months as they do at the better-known aggregation sites further north and south.

Because there is no boat ramp or town directly adjacent, Cod Grounds has historically been dived less than Fish Rock or Broughton Island, but Commonwealth marine park status and a full anchoring and mooring prohibition — introduced partly to protect underwater acoustic monitoring equipment tracking tagged sharks — have raised its profile and formalised how it must be dived. Divers descend on a shot line placed precisely by an operator who knows the pinnacle positions, since nothing is visible from the surface, and the site rewards divers prepared to work a genuine multi-level profile across the pinnacle tops and the deeper gutters around their base rather than expecting a single fixed route. Beyond the sharks, jewfish and kingfish schools move through the structure, and the deeper margins hold typical mid-north-coast temperate reef life.

Humpback whales and foraging seabirds use the surrounding water during migration. This is an advanced site by virtue of its depth range, offshore position and lack of any shallow refuge, and it is best dived with an operator experienced in placing divers accurately on the pinnacles.

Boat only, reached from the Camden Haven/Laurieton boat ramp (closer, roughly 20-30 minutes run) or as a longer trip from Port Macquarie (about 40 minutes). Anchoring and mooring are prohibited within the park to protect acoustic shark-monitoring equipment, so boats hold station or use a shot line for entry and exit — dive with an operator who knows the exact GPS position of the pinnacles, as they are not visible from the surface.

This stretch of coast is exposed to easterly and south-easterly swell with limited natural shelter; charters want under about 1.5 m swell and moderate wind to run safely, and the offshore pinnacle sites (Cod Grounds, Mermaid Reef, Yabbies) are cancelled first in marginal weather given the longer run and lack of lee. Visibility is best in autumn and early winter after a run of settled weather and drops noticeably after East Coast Lows and Hastings/Camden Haven River flood outflows. Grey nurse sharks are present year-round with numbers building through winter.

Descend the shot line onto the main pinnacle at around 18-21 m, then work around its base and the surrounding sand gutters and ledges at 26-32 m where grey nurse sharks typically hold, keeping the pinnacle in sight for navigation. Deeper divers can drop to the base of the formation near 40-46 m; plan a conservative profile given the depth range and moderate current.

Deeper sections of the pinnacle base approach or exceed recreational no-decompression comfort — plan multi-level profiles conservatively and monitor no-decompression limits closely given the depth range within one dive.

Scuba Haven (Port Macquarie) runs regular charters; local Camden Haven/Laurieton-based operators also run trips subject to demand and weather. A licensed operator is effectively required given the no-anchoring rule and remote pinnacle location.