The ex-HMAS Bayonet sits in 82 m of Bass Strait water off Cape Schanck — strictly a technical dive, way beyond recreational limits. The former patrol boat went down in deeper water than her sister wrecks and is reserved for divers running mixed-gas, full deco, twin sets and proper tech training. Marine growth on the wreck is dense — sponge gardens, gorgonians, schooling fish, and the occasional pelagic visitor cruising the depths. Visibility down there can be exceptional when the conditions line up but the trip out and the surface interval demand a settled forecast. Boat access only via charter, with skippers experienced in tech operations. Best in light north-east winds, swell under 1 m and tide near slack so the run out and the deco hangs are calm. Use the live 7-day forecast on this page to plan. Technical divers only — 82 m, full deco, gas planning.
How far you can see underwater — measured in metres. 10m+ is great, 5–10m is workable, under 3m is murk. Driven by wind, swell, and recent rain.
Long-period waves rolling in from the open ocean. Direction matters more than height — a S swell hits Portsea hard, but an E swell rolls past. Period over 12 s = real ocean punch.
Offshore (N or NE) flattens the surface and clears the water. Onshore (SE through SW) chops it up and stirs sand. Calm or light offshore is the magic combo.
This site faces the open ocean. The exposure caption above shows which directions slam in. Anything from the opposite side gets blocked — that's the safest window.
Slack water — the 30 minutes either side of high or low — is calmest and clearest. Mid-tide brings the most flow. Plan to be down at slack, up before the run picks up.
Bass Strait sits 14–16 °C autumn–winter, 17–19 °C summer. Below 16° a 7 mm hooded keeps you warm for 60 min+. Drysuit if you're going long.