Kirribilli Point is the most improbable dive in this file: a night dive in the inner harbour directly opposite the Opera House, below the Governor-General's Admiralty House and the Prime Minister's Kirribilli House, with the Harbour Bridge lit up a few hundred metres to the west. Michael McFadyen documented it as a site for the nights when the weather rules out everything else, and it has stayed obscure. The entry is easy – stairs from Lady Gowrie Lookout at the end of Kirribilli Avenue lead to a rock platform usable in nearly all weather – and the bottom is a mixture of sand and mud with outcrops of kelp, sections of rock wall and a cable or pipe that loops across the site, in 3–8 m.

The mud is the defining feature: it stirs at the slightest touch, so the dive is conducted with careful buoyancy at eight metres or less, close to the shore, and the route is a simple rectangle east, north, west and south along the wall. What lives there is more than one might expect: leatherjackets in profusion – pygmy, fan-bellied, velvet, mosaic, rough and yellow-finned – old wives, cuttlefish, small octopus, flathead and the occasional seahorse on the kelp. The lights of the Prime Minister's residence serve as a navigation mark on the return.

The overwhelming consideration is the ferries, which run between Kirribilli wharf and Circular Quay and pass over the site; divers are safe beneath them but must stay tight to the shoreline and surface only at the rocks, and McFadyen recommends the site 'only at night'. It is a dive for the curious and the experienced, for collectors of Sydney's odd corners, and for the night when a week of southerlies has closed the coast. Nobody guides it, and nobody should attempt it who is not comfortable in two metres of visibility under a ferry.

Drive to the eastern end of Kirribilli Avenue, Kirribilli (past Kirribilli House and Admiralty House) and park as close as possible to Lady Gowrie Lookout – residential parking, easier at night. Stairs lead directly from the lookout to a rock platform at the water, an excellent entry and exit in nearly all weather. The walk is negligible.

Exit at the same platform.

Kirribilli Point is deep inside the harbour opposite the Opera House and is untouched by swell; it is diveable in almost any weather, which is its only reason to exist as a site. Visibility is 2–5 m and drops to nothing after rain or if the easily stirred mud bottom is disturbed. Ferries between Kirribilli wharf and Circular Quay pass directly overhead and their noise underwater is, in McFadyen's phrase, 'very disconcerting'; dive only at night when traffic is lightest, stay close to the shoreline and never surface away from the rocks.

Descend off the platform over the small drop-off to 3 m and head east to 8 m, then north for five minutes following the kelp outcrops, west to the rock wall, and south along the wall for about ten minutes over the looping cable or pipe. Return west to the wall and follow it north past the two bright lights of the Prime Minister's residence before surfacing at the platform. Perfect buoyancy is essential over the mud.

No operator; the occasional adventurous independent night diver.