Long Reef Wall is the classic Northern Beaches boat dive and, with the adjoining Apartments, the site most Sydney charters run to when they head north. The reef is a ridge of Hawkesbury sandstone running roughly north–south off the tip of Long Reef Point, its top at 8–10 m. The eastern face steps down in a series of drops to about 15 m, where the wall meets a field of enormous fallen blocks, and beyond them the bottom slopes over boulders to sand at 20–24 m.

The wall itself is cut with cracks, overhangs and small caves, and it is the fixed growth here that makes the site: sea tulips, sponges, bryozoans and soft corals coat every shaded face. Two features define the dive. The Cathedral is a pair of massive slabs leaning together to form a peaked tunnel running east–west, tall enough to swim through upright; inside, thousands of ladder-finned pomfret hang in the gloom so that a midday dive feels like a night dive, and the exit frames blue water like a window.

Andy's Cave, further south at 15 m, is a more complex overhang under a slab tilted at 60 degrees, with several skylight exits; cuttlefish gather here, and fifteen have been counted in one visit. Between them the boulder field hides wobbegongs, Port Jackson sharks in winter and morays. Fish life is prolific: red morwong, bream, leatherjackets, silver sweep, yellowtail, sea pike and sergeant baker are constant, kingfish sweep past the outer boulders, and grey nurse sharks from the Apartments wander along the wall from summer to autumn.

Blue groper follow divers. Visibility is usually good enough to see the reef from the boat. The Wall suits everyone from newly certified divers, who can stay on the plateau and upper wall, to photographers who want the Cathedral's light.

It is the dive that introduced generations of Sydney divers to the north side, and the neighbouring Duckenfield wreck and Apartments mean charters can spend a whole day here.

Boat only. Sydney Dive Charters departs Little Manly boat ramp (Stuart Street, Manly – parking and set-up benches) or Rose Bay public wharf at 07:00 and runs north past North Head, Freshwater, Curl Curl and Dee Why to Long Reef Point, about 30–40 minutes in the Kevlacat; Dive Centre Manly and Pro Dive Manly leave from Manly Cove/Little Manly on similar timings. Private boats launch at Roseville Bridge (Middle Harbour) or from Pittwater (Careel Bay/Bayview, 40 minutes south past Bungan and Mona Vale).

The reef is visible from the surface in good visibility; boats anchor on the plateau in about 10 m and divers descend the anchor line to the wall. No moorings.

Long Reef Point projects further east than any other Northern Beaches headland and takes swell from south through east to north-east. The reef top breaks in anything over about 1.5 m, and surge on the wall is uncomfortable above 1.2 m from the east or south-east; charters cancel or move to North Head when the swell is up. Wind chop from a strong north-easter makes the afternoon anchorage rough, so morning dives are the rule.

Visibility is usually 10–20 m, best in the cooler months (May–September) when the water is clear and 16–18 °C; summer brings warm 22–24 °C water, more plankton and the grey nurse build-up from December to May. Run-off from Dee Why Lagoon and Narrabeen Lakes after heavy rain dirties the inshore water for a few days.

Anchor in about 10 m on the plateau and drop to the base of the wall at 15 m. Head east across the large boulders to find the southern entrance of the Cathedral, swim through beneath the leaning sandstone slabs to the 'altar' and out the northern 'window', then circle the boulders anti-clockwise back to the main wall. Work south along the wall investigating overhangs and Andy's Cave (a 60-degree slab with several skylight exits at 15 m), and return north to the anchor.

Safety stop on the plateau at 8–10 m.

Sydney Dive Charters – guided double boat dives Thursdays and Sundays (07:00) from Little Manly ramp/Rose Bay, Long Reef sites most weeks in season; Dive Centre Manly – weekend boat dives from Manly; Pro Dive Manly – weekend double boat dives; Frog Dive and Abyss occasionally on club trips. Private boats from Roseville, Pittwater and Rose Bay ramps.