North Wall is the deep wall on Spectacular Reef, the limestone ridge that runs along the southern edge of the Queenscliff bank inside the Heads. The Scuba Doctor listing, with GPS from the Power House Underwater Club, places it between Captain Nitro Drop Off and Spec Reef, gives the top of the wall at about 19 m and says the face 'drops over 60 metres'. It describes 'large overhangs, small caves, swim-throughs and lots of crevices to explore' and southern rock lobster on the top of the wall.

This is the same drowned-valley geology as Lonsdale Wall but on the northern, Queenscliff side of the channel, facing south into the deep water of the entrance. Because it is a little further inside the bay than the Lonsdale sites it is more sheltered from swell and the listing rates it as diveable in most weather, with the qualification that big seas outside cut visibility to a couple of metres for a day or two. The encrusting life is the full Heads assemblage – sponges, zoanthids, soft corals, gorgonians in the deeper overhangs – and blue devils, boarfish, old wives and morwong hold the caves, with sevengill sharks in the deeper water and dolphins and seals passing in mid-water.

The complication is position: North Wall lies directly in the shipping channel, so it cannot be anchored, and a shipping report from Lonsdale VTS is a condition of the dive. With the top at 19 m there is no shallow ground, and the 60 m base makes it a regular technical destination; recreational Advanced divers dive the upper terraces on a short slack-water profile. It is a club and technical-charter site more than a daily drop, and together with Captain Nitro Drop Off and The Far Side it forms the deep-wall trio on the Queenscliff side. Note that 'North Wall' here is distinct from North Wall Corner on Lonsdale Wall.

Boat access only. Charter boats leave from Portsea Pier (Dive Victoria Group, Bayplay) and Queenscliff Harbour (Dive Victoria Group, Red Boats); run time is about 12 minutes. Private boats launch at Sorrento Boat Ramp (Point Nepean Road, Sorrento, all-tide concrete ramp with trailer parking) or Queenscliff Boat Harbour ramp (Larkin Parade, Queenscliff), roughly 10 minutes to the site.

The site is inside the bay off Shortland Bluff on the Queenscliff side, 10 minutes from Queenscliff Harbour and about 15 from Portsea; GPS is from the Power House Underwater Club. Skippers must call Lonsdale VTS (Point Lonsdale) or listen to VHF 12 for shipping movements before dropping divers, and must carry a dive flag; anchoring is not permitted in the shipping channel, so a live boat and a drop-shot or drift float is the normal method. Anchoring is prohibited – the listing states you 'must get a shipping report from Point Lonsdale or the Seapilot Station prior to diving'.

It is dived only on slack water, either at the end of the flood (SWF) or the end of the ebb (SWE); most operators prefer the flood slack so that any residual current sets into the bay rather than out to sea. Slack water at Port Phillip Heads does not coincide with high or low water: it falls roughly three hours after high or low water at Point Lonsdale, and the usable window is typically 20–40 minutes. Use the Ports Victoria / Port of Melbourne slack-water predictions for The Heads (also republished by charter operators and WillyWeather 'Rip Bank') rather than a standard tide table.

Inside the Heads it is sheltered from most swell, but a south-west swell over about 2 m still surges across the top of the wall and a westerly or south-westerly wind over 15–20 knots makes the boat work unpleasant; big seas outside drop visibility to a few metres for a day or two. Visibility is best in late summer and autumn (Feb–May) when the water is clear and the westerlies have eased; winter brings 11–13 °C water and bigger swells but often the clearest days after a run of settled weather. Heavy rain has little effect this close to the ocean.

The listing notes it is 'diveable in most weather conditions, however big seas will reduce viz to a couple of metres'.

Shot onto the wall top at 19 m at slack. Drop over to the first big overhang at 25–30 m and work along the face through the small caves and swim-throughs, technical divers continuing to 40–60 m. Return to the shot line area, ascend the wall to the top, DSMB and drift while the boat tracks.

Base 60 m+; trimix; no anchoring, shipping report mandatory; drift deco under DSMB with tracking boat. Rebreather friendly.

Dive Victoria Group (Portsea/Queenscliff) – runs the deep Heads walls for advanced and technical divers on suitable slack-water days; Red Boats (Queenscliff) – deep-wall and technical charters on request; otherwise private club boats (VSAG, Power House Underwater Club, Scuba Diving Melbourne). Not a routine training-boat site.