Bluefish Valley is a natural amphitheatre cut into the base of the North Head cliffs beside Bluefish Point, a gully with sheer walls on both sides and a floor of kelp-covered boulders at about 7 m, opening onto the reef edge at 16 m. It is the northern counterpart of Magic Point at Maroubra: a grey nurse shark colony and mating site where the critically endangered sharks are present all year, typically 10–20 animals from 1.5 m juveniles to 3.5 m adults, with numbers building from December to a peak in April and May. Sydney Dive Charters, which developed the site as a guided dive, rates it Open Water level and ideal for first boat divers because it is shallow, enclosed, and almost never has current or surge.

The sharks are the reason to come, but the valley holds a lot else. Giant cuttlefish sit among the boulders, wobbegongs sleep in the kelp, big blue groper follow divers, octopus and moray eels occupy the cracks, southern pomfret and old wives school under the walls, and bull rays, eagle rays and weedy sea dragons are all regular. The walls carry soft corals and sponges in the shade.

Visibility is the same as Bluefish Point, often 15 m and occasionally 40 m in winter blue water. Grey nurse sharks are protected and a code of conduct applies at all aggregation sites: no more than a small group in the gutter at a time, stay low and to the side, no touching, feeding, chasing or flash directly in their eyes, and no scooters. Because the valley is enclosed, disciplined behaviour matters more here than at open sites, and the operator keeps groups small for that reason.

It suits new divers who want a shark encounter in gentle conditions, photographers with wide-angle lenses, and anyone diving Manly between December and June; it pairs with Bluefish Point or the North Head sponge gardens for a second dive.

Boat only. Dive Centre Manly loads at Manly Cove beach beside the wharf; Pro Dive Manly and Sydney Dive Charters load at the Little Manly boat ramp (end of Stuart Street, Manly – free parking, set-up benches, toilets at the reserve); Sydney Dive Charters also picks up at Rose Bay public wharf. From Manly the run is 10–15 minutes from Manly Cove around the Shelly headland to the Bluefish Point area on the ocean side of North Head; Sydney Dive Charters runs it from Little Manly and Rose Bay, 20–25 minutes from Rose Bay.

Private boats launch at Little Manly, Roseville Bridge (Middle Harbour, 30 minutes) or Rose Bay. Boats anchor on the reef in 15–20 m or run in toward the cliff and drop the anchor when the bottom appears; there are no moorings, and many abandoned anchors litter the reef.

Bluefish Point and the outer eastern end of North Head face the open Tasman Sea and are exposed to south, south-east and east swell; surge is heavy in anything over 1.5 m and charters move inside the Heads. North-easterly sea breezes make the afternoon uncomfortable, so dives are in the morning. Current is usually mild but can run along the point on the tide.

Visibility is typically 10–20 m, best in the cooler months (May–September) when grey nurse and Port Jackson sharks are also present; the old Manly sewage outfall at Bluefish was decommissioned in the 1990s but the water is still dirtier for a day or two after heavy rain. The valley itself is described by the operator as protected from wind and waves with rarely any current, so it is often diveable when the point outside is surging.

Descend on the reef edge at 16 m outside the valley, then swim slowly into the valley along the 7 m floor with the walls either side, settle low against one wall and let the grey nurse sharks come past; do not block the valley or chase. After 15–20 minutes with the sharks, tour the kelp boulders for cuttlefish, sea dragons and wobbegongs, and finish with a safety stop on the shallow reef at 5 m.

Sydney Dive Charters – guided grey nurse shark double dives most Thursdays and Sundays in season, small groups, Open Water level (10 boat dives recommended); Dive Centre Manly and Pro Dive Manly visit the Bluefish area regularly and drop into the valley when sharks are present.