Nelson sits at the mouth of the Glenelg River on Victoria's far western coast right near the South Australian border — the most westerly dive sites in the state. The river mouth has a bar that requires local knowledge to cross, and offshore reef sits in around 14 m of Bass Strait water. The freshwater outflow from the Glenelg can affect visibility on the inshore reefs but the offshore sites are richer — kelp gardens, sponge cover, crayfish, abalone, weedy seadragons, blue devils, schools of sweep and the occasional pelagic visitor. Boat access from the Nelson ramp on settled days. Best in light north-east winds with swell under a metre and tide near slack through the bar. Use the live 7-day wind and swell forecast on this page to plan. Intermediate to advanced — the bar crossing is the main hazard, freshwater can blow visibility on the river-side sites, settled forecast non-negotiable.
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.