Sponge Garden Drift is the gentlest introduction to what makes the Heads special. The Scuba Doctor listing places it inside Port Phillip off Queenscliff at 12–20 m, dived on the ebb, and describes a drift whose terrain 'transitions progressively from shallow reefs to sponge gardens, then to larger reef formations and bommies', with sponge coloration as 'the primary visual appeal'.

The sponge gardens of the Lonsdale Bight and Queenscliff bank are a consequence of the tide: the filtered plankton of the whole bay passes over these reefs twice a day, and the low rock is covered in a continuous carpet of sponges in orange, yellow, purple, red and white, with ascidians, bryozoans, hydroids and small gorgonians between them. On the drift the garden unrolls beneath the group at walking pace. Fish populations, the listing notes, vary with the terrain – leatherjackets, wrasse and magpie perch over the shallow reef, blue devils and sweep around the bommies – and the sponges themselves are the habitat for nudibranchs, sea stars, sea spiders and the small crustaceans that macro photographers come for. Seahorses and pipefish are found in the hydroids.

The listing adds a detail that hints at the history of the ground: 'historic artefacts including old bottles and collectible items are occasionally encountered', the debris of a century and a half of ships anchored off Queenscliff. (These are protected and should be left in place.) Rated Advanced for the drift technique rather than the depth, this is in practice an easy, sheltered dive that operators use for the second dive of the day, for drift-diving instruction and on days when the walls are unworkable. Torpedo Reef, another Queenscliff sponge site, is 290 m away.

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 10 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 8 minutes to the site.

The site is just south-east of Queenscliff inside the bay, under 10 minutes from Queenscliff Harbour and about 15 from Portsea. 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. Run as a group drift on a flagged float line on the ebb.

It is dived on the ebb slack or a gentle ebb only, when the outgoing tide leaves this side of the reef in relatively still water. 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.

Scuba Doctor lists 'dive only on: Ebb'. Well inside the bay, it is one of the most sheltered Heads-area dives and is usually workable when swell rules out the walls.

Enter at the shallow-reef end on the early ebb, descend the float line to 12 m and drift with the tide as the bottom changes from shallow reef to sponge garden to larger reef and bommies at 18–20 m. Stay with the float; the boat retrieves the group after 40–45 minutes.

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.