Watsons Bay Pool is one of Michael McFadyen's odder harbour finds: a pair of netted swimming enclosures beside Doyles restaurant that, at night, turn out to be a first-class critter dive. The older pool is about 50 m square, fenced from the sand to the boardwalk by vertical bars rather than net; the newer section, about 20 m long, is offset 5 m to the south, and white-painted arches carry the boardwalk over the bars on the northern side. The bottom is rock with a great deal of kelp and weed, a small rock overhang and a rock platform, and heaps of debris – timber, rusty steel and general rubbish – that provide as much habitat as the kelp.

Depth is 2 m at the beach and 6 m or more at the outer bars. The residents are the harbour's classic small animals in unusual density: White's seahorses on the kelp and sponges, pygmy leatherjackets from 10 to 75 mm, blue-ringed octopus, nudibranchs, cuttlefish, pineapplefish under the ledge, crabs, whiting, flathead, small rays and flounder on the sand, and tube anemones and sea pens standing out of the sediment. It is a torch-and-macro-lens dive; by day the swimmers own the pool and the animals hide.

Depth and conditions are trivial, so it is an ideal first night dive and a fallback when a big swell closes the ocean and even Camp Cove is chopped up; the pool structure keeps boats away and the bars make navigation foolproof. The two difficulties are the high drop from the boardwalk (use the beach at high tide) and parking, which in summer is close to impossible near the pool. Watsons Bay Pool suits night divers, photographers and beginners, and can be combined with fish and chips from Doyles or a pint at the Watsons Bay Hotel, which is not nothing.

Take Old South Head Road past The Gap into Watsons Bay and turn down to Marine Parade; a small car park on the right beside the Vaucluse Yacht Club and Doyles restaurant is the closest (very hard to find a space in summer; the main Watsons Bay car park behind the hotel is 300 m away). Walk 50 m along Marine Parade to the pool boardwalk. Entry is a high drop from the boardwalk between the old and new pool sections, or a gentler wade from the little beach beside the pool at high tide.

Exit by the ladder or the beach.

Inside South Head the ocean swell is broken; the eastern harbour shore dives are exposed only to wind chop and, in the case of Camp Cove and Green Point, to a north-westerly or northerly blow that puts a short sea onto the beaches. They are at their best in a southerly, which flattens them completely, and on the top of a flood tide when clean ocean water has come in through the Heads (visibility 5–10 m; 15 m on a rare winter day). After heavy rain the harbour is brown for days and the dives are not worth doing.

Boat and ferry traffic is intense on summer weekends and public holidays, when the bays fill with anchored craft; early mornings, weekdays and nights are the times to dive. The pool faces west and is sheltered from everything but a westerly chop; the ferry wharf is 200 m away and the pool structure keeps boats out. Swimmers use it all day in summer, so it is a night dive in practice.

Drop in under the boardwalk and head west along the bars of the old pool, south to the corner of the newer pool, west 20 m, then north 50 m along the rocky, kelp-covered bottom; follow the bars north under the white-painted arches and return the same way, searching the kelp, sponges and rubbish for seahorses, pygmy leatherjackets and blue-ringed octopus.

Dive 2000 and Abyss occasionally run night dives here; otherwise independent night divers and photographers.