Lonsdale Wall is a boat-access wall dive on the Point Lonsdale side of Port Phillip Heads. It is part of a wider group of named wall sites, so the name alone is not enough to establish where a charter will dive. The published coordinate used here identifies the 12–38 m Lonsdale Wall listing, rather than the separate Lonsdale Wall Shallow site.

Parks Victoria describes the ledges as part of the historical Yarra River course. This gives the site its defining attraction: underwater relief, with different levels to observe rather than a single flat reef. The useful planning question is which section and depth your operator intends to use, not whether you can reach the maximum number in a directory.

Arrange a boat departure with a local dive operator. Confirm the harbour, check-in time and meeting address directly; the site coordinate is offshore, not a departure point.

Slack-water planning and an on-site assessment are required. Consult current forecasts and the operator; this record does not provide live conditions.

The boat drops a weighted shot on the lip of the wall in 12–18 m a few minutes before predicted slack. Descend the shot, orient with the wall on your left (deeper water to the east/south), and drop straight to your planned maximum – 30 m for a standard Advanced profile – then work back up the terraces, spending most of the dive between 18 and 25 m where the overhangs are richest. Turn at 20–25 minutes or when you feel the current begin to build, ascend the wall face to 12 m, launch a DSMB from the reef top and do the safety stop drifting in open water; the live boat follows the float.

Dive Victoria Group (Portsea and Queenscliff) – double boat dives to the Heads walls most days of the week, site chosen on the morning by slack-water time and swell; Bayplay Adventure Tours (Portsea) – weekend and holiday charters; Red Boats (Queenscliff) – weekend Heads charters; Melbourne clubs (VSAG, Power House Underwater Club, Scuba Diving Melbourne) run their own boats here regularly.