Shortland Bluff Bommie – Bluff Bommie to the locals – is a small site with a large reputation. The Scuba Doctor listing gives it 18–20 m and an Advanced Open Water rating and then says, in a single sentence, everything that matters: it is 'one of Victoria's scariest dives with fierce tidal currents and a narrow slack water window'. It lies just off Shortland Bluff, the headland at Queenscliff on which the lighthouses and Fort Queenscliff stand, where the flow out of the Queenscliff channel meets the main tidal stream of Lonsdale Bight.

The bommie itself is a limestone outcrop on a flat bottom at 20 m, and its interest is that of any current-swept rock at the Heads: dense encrustation of sponges, zoanthids and soft corals on the up-current faces, crayfish and blue devils in the undercuts, and fish holding in the eddy behind it – sweep, boarfish, old wives, magpie perch. The listing publishes no species list and the description here is drawn from the adjacent Boarfish Reef Drift ground 100 m away, which covers the same reef system.

What sets it apart is the water. Because it sits at a junction of tidal streams, the slack here is shorter than almost anywhere else inside the Heads and the current, when it comes, comes at once and hard. The dive is therefore a matter of being on the shot at the predicted minute, circling the rock for a quarter of an hour, and leaving before the stream builds – with the boat live and a DSMB ready. It is dived rarely, by Queenscliff club divers who know the timing, and it is not a site for anyone's first Heads dive; but for experienced current divers who want to see what the tide does to a rock in its path, it is instructive. Data confidence is moderate.

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 8 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 6 minutes to the site.

The site is just off Shortland Bluff on the Queenscliff side, six minutes from Queenscliff Harbour; the position at the corner where the Queenscliff channel meets the Lonsdale Bight flow gives it a very short slack. 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.

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 calls it 'one of Victoria's scariest dives with fierce tidal currents and a narrow slack water window' – the boat must be on station early and divers in and out inside a very few minutes of the turn.

Shot onto the bommie at 18 m exactly at predicted slack. Circle the structure once or twice at 18–20 m in the lee, keep the shot in sight, and leave the bottom at the first pull of current – often within 15–20 minutes – ascending under a DSMB for a live-boat pick-up.

No regular scheduled charter – dived from private and club boats (VSAG, Power House Underwater Club, Scuba Diving Melbourne) and occasionally by Dive Victoria Group or Red Boats when a group requests it.