Ray Alley is a shallow, gentle North Head site defined by its residents rather than its topography: a sandy alley running between the boulder reef and the deeper sand where, as Sydney Dive Charters puts it, 'resident large black bull rays' are found on most dives. Southern eagle rays and smooth stingrays also use the gutter, and the sand between the rocks is where weedy sea dragons, stingarees, flathead and the occasional numb ray are found. The reef edge that borders it is standard inner-North Head boulder slope with kelp on top, sponges and soft corals underneath, wobbegongs and Port Jackson sharks under the ledges and blue groper in attendance.

At 10–20 m it is the shallowest of the North Head anchorages and one of the best for newly certified divers, photographers who want long bottom times with large animals, and night dives, when the rays are active and the boulder faces come alive with basket stars, decorator crabs and hunting octopus. Giant cuttlefish are common in winter and spring. Because the rays are habituated they tolerate careful approach, but they are large wild animals with a venomous spine; the operators brief divers to stay off the bottom and never to corner one against the reef.

The site is on the sheltered harbour face inside the North Harbour Aquatic Reserve and is diveable in almost all weather short of a large southerly swell; tidal current is light. Visibility is 8–15 m, sometimes better in winter. Ray Alley suits Open Water divers, families with a mix of certification levels, and anyone who has done the deeper sites and wants a slow dive with big rays; it is usually paired with Bluefish Point or Old Man's Shoulder as the second, shallower dive of a Manly double.

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 across North Harbour to the inside of North Head, 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.

The inner face of North Head is the most sheltered ocean-quality diving in Sydney. It faces west-south-west into the harbour, so it is protected from the north-east sea breeze and from northerly and easterly swell, and is at its best when a strong north-easter is blowing and every ocean site is rough. It is exposed to southerly swell rolling through the Heads: a big southerly (over 2 m) sends surge along the cliff and dirties the water, though the deeper sponge gardens are usually still diveable.

Tidal current runs along the wall, east on the flood and west on the ebb, strong enough to plan a drift; slack water is easiest for novices. Visibility is 10–15 m on average, 25 m on winter westerlies, and drops after heavy rain when the harbour flushes brown. Ferry, shipping and small-boat traffic through the Heads is constant – ascend on the anchor line or a DSMB close to the cliff.

Descend to the sand gutter at 14–16 m and swim its length slowly, staying a couple of metres off the bottom so the rays are not disturbed; then follow the boulder edge back at 10–12 m looking for sea dragons, cuttlefish and octopus. Long safety stop on the shallow reef by the anchor.

Sydney Dive Charters – on its North Head rotation of guided double dives (Thursday/Sunday), often as the shallow second dive; other Manly operators dive the same ground under the general North Head label.