Diamond Bay is a small south-facing cove on the Sorrento back beach side, with reef diving in around 12 m. The bay is bordered by rocky headlands which give a touch of shelter compared to the open beaches either side, but it's still ocean swell territory. Marine life is the standard back-beach mix — crayfish, abalone, weedy seadragons, blue devils, sweep, and plenty of kelp and sponge cover. Shore entry is via the steep stairs from the Diamond Bay lookout car park. Diveable in light northerlies with swell under a metre and tide near slack water. South or south-west swell wraps in and shuts it down. Use the live 7-day wind and swell forecast on this page to pick your slot. Intermediate divers — steep stairs to carry gear, surf entry, exposed conditions if the swell is up.
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.