The Quarantine Station Anchor is a single large ship's anchor lying on the sand of Ticonderoga Bay off the Point Nepean Quarantine Station, listed by Scuba Doctor as a wreck dive in 10–12 m for Open Water divers at slack water. It is one of the many anchors lost or slipped by the immigrant ships that anchored off the station between the 1850s and the 1950s – the Quarantine Station Reef listing counts six more on the ridge 1.2 km to the west – and it has been catalogued as a site in its own right because it is isolated, easy to shot and large enough to fill a shallow dive.

The listing carries no description beyond position, depth and gear; the anchor is of the stocked Admiralty pattern typical of the sailing-ship era, several metres long, heavily concreted and grown with sponges, hydroids and ascidians, and it functions as a small artificial reef on an otherwise bare sand plain: leatherjackets, goatfish, wrasse and bullseyes gather on it, octopus and cuttlefish den beside it, and the surrounding sand holds stingrays, fiddler rays, spider crabs in season and the seahorses and pipefish of the Ticonderoga Bay sand. Bottles and other artefacts turn up in the sand around it as they do across the bay, and are protected.

It is a modest site, used by Portsea operators for Open Water training and navigation practice – the recommended reel and SMB are for exactly that, because a single object on flat sand is easy to lose in 5–10 m visibility – and by private boats wanting a sheltered, short, shallow dive close to Portsea. Combined with Artefacts Flood and Quarantine Station Reef it forms a trio of historic-seabed dives in the bay.

Boat access: five minutes west of Portsea Pier by charter or 10–15 minutes from Sorrento Boat Ramp by private boat. The anchor sits on open sand at 10–12 m and is shot directly on the GPS; boats anchor on sand clear of it. Dive flag required – the South Channel and ferry route pass to the north.

The listing recommends a reel and SMB, since the anchor is a single object on a featureless bottom and is easy to lose.

It is dived only on slack water, either at the end of the flood (SWF) or the end of the ebb (SWE); most operators prefer the flood slack so that any residual current sets into the bay rather than out to sea. Slack water at Port Phillip Heads does not coincide with high or low water: it falls roughly three hours after high or low water at Point Lonsdale, and the usable window is typically 20–40 minutes. Use the Ports Victoria / Port of Melbourne slack-water predictions for The Heads (also republished by charter operators and WillyWeather 'Rip Bank') rather than a standard tide table.

Inside the Heads it is sheltered from most swell, but a south-west swell over about 2 m still surges across the top of the wall and a westerly or south-westerly wind over 15–20 knots makes the boat work unpleasant; big seas outside drop visibility to a few metres for a day or two. Visibility is best in late summer and autumn (Feb–May) when the water is clear and the westerlies have eased; winter brings 11–13 °C water and bigger swells but often the clearest days after a run of settled weather. Heavy rain has little effect this close to the ocean.

Sheltered Ticonderoga Bay water, workable in all but strong northerlies; visibility 5–15 m over sand.

Descend the shot onto the anchor at 11 m at slack, tie off a reel and run a circular search of the surrounding sand for other artefacts, returning to the anchor; ascend the shot. A good Open Water navigation exercise.

Dive Victoria Group and Bayplay (Portsea) – occasional, as an Open Water training or navigation dive; private boats from Sorrento.