Forty Baskets is the little beach below Dobroyd Head on the North Harbour shore, named for a catch of fish sent to soldiers quarantined at North Head in 1885, and it is the nearest access to the Dobroyd Head reef for shore divers. Diveplanit lists it as a 'shallow shore dive with netted pool and rocky outcrop south of beach', and that is the dive: a netted swimming enclosure whose mesh holds White's seahorses, a seagrass and sand floor at 3–6 m, and, to the south, a rocky outcrop of boulders that drops to a sand line at 8–10 m and continues as the Dobroyd Head reef toward Crater Cove. To the north, 700 m of shore leads to Reef Beach.

The VIZ club's Dobroyd Head survey records seahorses near Forty Baskets, juvenile Port Jackson sharks, Australian angelsharks, crested horn sharks, a banded wobbegong, stonefish, moray eels, a juvenile hammer octopus, kingfish schools passing offshore and blue-and-yellow fusiliers among the tropical visitors; sea urchins and sea tulips crowd the boulders. All of that is inside the North Harbour Aquatic Reserve, where nothing may be collected. The limits are severe visibility – 2–3 m with a layer of particles hanging near the bottom, so that the club found compass work unreliable and simply followed the rocks – the Manly ferry passing 'at full power' a few hundred metres off, and the 700 m walk from Beatty Street with gear.

Night dives solve the boat problem and improve the animals. Forty Baskets suits patient Open Water divers, night divers and seahorse hunters who want a reserve site nobody else is on; for structure and visibility, Fairlight across the water is easier.

Park in Beatty Street, Balgowlah Heights (small free car park at the end) and take the Manly Scenic Walkway path down to Forty Baskets Beach – about 700 m, mostly flat then descending, 'a long way with tanks and gear' but manageable, and done at night by the VIZ club. Gear up on the grass, enter from the sand beside the netted pool and swim south to the rocky outcrop or north along the shore toward Reef Beach. Exit back onto the beach and walk up.

Deep inside the harbour these sites see no ocean swell; only a strong southerly or south-easterly wind raises a chop, and even then the dive usually goes ahead. What matters is water quality and tide. Dive on the incoming tide or at high water, when the flood brings cleaner ocean water up the harbour and the shallow margins have enough depth; low tide exposes rock and shortens the dive.

Visibility is normally 3–7 m and can reach 10 m on a winter flood; after heavy rain the harbour runs brown for several days and visibility drops to a metre. Boat traffic is heavy on summer weekends. Night dives are the best dives.

Forty Baskets faces east across North Harbour and takes the wash of every Manly ferry passing 400 m away; otherwise it is sheltered. Visibility is poor – 2–3 m is common, with a layer of heavy suspended particles near the bottom – so navigation by compass is unreliable and the reef should be followed by touch and sight of the rocks.

Enter beside the net and check its panels for seahorses at 2–4 m, then swim south along the shore to the rocky outcrop and follow its boulders down to the sand at 8–10 m; turn at half air and return along the same rocks, or on a second dive head north over kelp and sand toward Reef Beach. Stay close to the rocks and surface only near the beach.

No operator runs it regularly; VIZ dive club surveys, occasional Dive Centre Manly club nights, independent divers and snorkellers.