Moolap Reef, also recorded as the Outer Harbour Shellfish Reef, is not a dive site in the usual sense but a restoration project that happens to be diveable. Port Phillip once had vast beds of native flat oysters and blue mussels that were dredged out by the early twentieth century, and since 2015 the Victorian Fisheries Authority, The Nature Conservancy and the Albert Park Yachting and Angling Club have been rebuilding shellfish reefs at several sites in the bay, including here in the outer harbour of Corio Bay between Point Henry and Point Richards. The method is to lay a base of limestone rubble and recycled shell on the mud and seed it with hatchery-reared oysters and mussels, and the result is a low, broad mound in about 10 m of water that is steadily being colonised.

The name Moolap is from the Wadawurrung language and is said to mean a place of men fishing with spears. For a diver the reef is a flat, easy 10 m dive with a purpose: to see how quickly shell structure on bare mud attracts life. Within a few seasons the rubble is grown with ascidians, sponges, hydroids and algae, native oysters are visible among the shell, and the mound holds snapper, leatherjackets, wrasse, gobies, blennies and cuttlefish, with flathead, rays and the introduced Northern Pacific seastar on the mud around it.

It is used mainly by research and monitoring divers and occasionally by Geelong clubs, is unmarked on the surface, and is fished, so a flag and care with line are needed. The nine Wilson Spit shellfish reefs lie 3 km east and can be dived on the same outing.

Launch from the Limeburners Point ramp in Geelong or the Point Richards ramp at Portarlington on the southern shore (20-30 minutes' run), or from the Avalon Beach or Geelong Grammar lagoon ramps on the northern shore. The reef is a low mound of shell and limestone rubble on flat mud, unmarked on the surface, so use the published position and a sounder, anchor on mud beside it and descend the line. Not reachable from shore.

Open water in the middle of the outer harbour: light winds only, from any direction under about 10 knots, as there is no lee. Visibility is generally modest (2-5 m) over the mud and is best on the high tide in winter after dry weather; the Barwon, Moorabool and Hovells Creek plumes reduce it after rain. No swell.

Ships use the Corio Bay channel to the north, so anchor well clear of it.

Descend the anchor line to the mud at 10 m, find the edge of the shell mound and work around it slowly at 8-10 m keeping the reef on one shoulder, look for the native flat oysters and mussels among the rubble and the fish above them, return to the line at half gas and ascend with a stop at 5 m.

No regular operator – private boats, Bay City Scuba club boat and research divers from The Nature Conservancy's shellfish reef program.