Offshore reefs at Apollo Bay on the Great Ocean Road sit in around 22 m of Bass Strait water, exposed to swell from south through south-west. The Otway Ranges behind the town give some shelter from north-quadrant winds but the open-ocean swell is the main game. Reef holds crayfish, abalone, weedy seadragons, blue devils, kelp gardens, sponge cover, gorgonian fans on the deeper edges, plus regular pelagic visitors and Australian fur seals from the nearby colonies. Boat access only, from the Apollo Bay harbour. Best in light north-east winds with swell under a metre and tide near slack. Use the live 7-day wind and swell forecast on this page to plan. Advanced divers — exposed Otway coast, current on tide change, several kilometres offshore for the better reefs, settled forecast non-negotiable for the run out and back.
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.