The outer half of Chowder Bay is a different dive from the seahorse net at Clifton Gardens, and Michael McFadyen documents it on its own page. East of the public wharf the bay opens out toward the long naval wharf built for the submarine-mining depot in the 1890s and used by the Navy into the twentieth century; between the two lie the heavy anchor chains that once secured warship mooring dolphins, running across the sand to concrete blocks at 10–11 m, a forest of old timber piles, mooring buoys and their gear, and a scatter of larger objects – a small yacht and a launch that sank on their moorings, an Admiralty-pattern anchor, and a Land Rover that somebody put over the side. Depths are 6–8 m on the crossing and 10–12 m under the naval wharf and out at the mooring blocks.

The structure attracts more fish than the inner bay: schools of yellowtail and bream around the big piles, snapper and wrasses in the shadows, moray eels in the chain links, decorator crabs and White's seahorses on the chains themselves, cuttlefish and squid on the sand, and, in season, tropical juveniles along the wharf. Sponges, ascidians and soft growth coat the piles and chains in a way the sandy inner bay cannot match. The dive takes planning: it is a 150–200 m crossing each way over featureless sand in 3–7 m visibility, the moorings are in use, and the naval wharf and HMAS Penguin grounds are restricted above the waterline, so the normal method is a compass run from the public wharf along a chain and back.

Plunge Diving, based on the naval side, guides it and can arrange access there. It suits Open Water divers with sound navigation, photographers who want structure as well as critters, and night divers who have exhausted the inner bay.

As for Clifton Gardens: Morella Road, Mosman, paid car park, out along the public wharf on the left of the swimming net. From the end of the wharf swim (surface or at 6–8 m) east-south-east across the bay toward the large naval wharf and mooring buoys, following the anchor chains that run out to the old mooring dolphins. Access through the Georges Head/HMAS Penguin road to the naval side is possible only with Plunge Diving's approval.

Return on a reciprocal bearing to the public wharf; do not surface among the moorings.

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.

The outer wharf and moorings are exposed to the wash of ferries and vessels rounding Bradleys Head, and yachts use the moorings; a DSMB or float is sensible for the crossing.

From the public wharf descend to 5 m and take a bearing east-south-east along the sand, picking up the first anchor chain and following it out to its mooring block at 10–11 m. Work between the chains, timber piles and the big naval-wharf piles, visit the yacht and launch wrecks, the Admiralty anchor and the Land Rover, then return along the next chain to the swimming net and the public wharf. Allow 15 minutes each way for the crossing; turn on a third of your air.

Plunge Diving – guided 'outer' Chowder Bay dives from its base beside the naval wharf; Dive Centre Manly, Dive 2000 and Frog Dive guide experienced divers out to the chains and wrecks on longer dives.