Cottage by the Sea Reef is Queenscliff's shore dive, named for the historic children's holiday home that has stood on the bluff above it since 1890. The Scuba Doctor listing gives a depth range of 1–10 m from the shore and a separate boat mark on the outer reef 400 m out, rates it Open Water and beyond, and puts it at the western end of the Queenscliff front beach where the Lonsdale Bight sponge reefs run in toward the shore.

The bottom is broken limestone ledges and gutters with kelp and seagrass in the shallows, deepening to sponge-covered reef and sand at 8–10 m. The listing's species list is long for a shore site and reflects the influence of the Heads a couple of kilometres away: Australian fur seals, smooth stingrays and southern fiddler rays on the sand, giant Australian cuttlefish in winter, southern blue devils and old wives under the ledges, weedy seadragons on the seagrass edge, southern rock lobster in the gutters, and the everyday reef fish – damselfish, morwong, wrasse, bluespotted goatfish, leatherjackets – over the top. Sea stars are abundant on the sponge patches.

It is dived at low water on the ebb slack, because the flood runs east along the shore toward the Queenscliff channel and can be strong, and it is protected from northerly to westerly winds, which makes it a useful fallback when the bay-side piers are blown out. The main hazard is traffic: boats and personal watercraft use the bight heavily in summer and a float and flag are mandatory. For divers based in Queenscliff who want a shore dive with real Heads fauna – seadragons, blue devils, seals – without a boat, this is the one.

In Queenscliff drive to the southern end of Swanston Street where it meets The Esplanade; there is a small reserve with parking for a handful of cars (Melway 499 C12, beach marker 9B). From the car park it is a short walk down the stairs and across the sand to the rocky platform below the Cottage by the Sea camp – 100 m or so – and the entry is 'straight out to the sea' from the platform, which is visible at low tide. Exit the same way.

Boats from Queenscliff Harbour (5 minutes) drop divers on the outer reef at the boat mark 400 m offshore. Air fills Dive Victoria Group, Queenscliff Harbour (1.5 km).

Best at low water at the Heads and dived 'during slack water to ebb tide'; the listing warns the 'current can be quite strong otherwise' – the flood runs east along this shore toward the Queenscliff channel. 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.

Conditions are 'usually best with no wind or after a few days of northerlies'; the site is protected from northerly through westerly winds but open to the south-west, and swell wrapping into Lonsdale Bight makes it surgy. Visibility 5–12 m, best in autumn. A dive float with flag is mandatory because of heavy boat and jet-ski traffic in the bight.

Enter from the platform at low water on the ebb, swim straight out over the shallow ledges to the reef at 6–10 m, work east or west along the ledges and gutters for 20 minutes, and return on a reciprocal heading to the platform; tow a float and flag the whole way and stay well inside the boat channel.

Dived independently and by Bellarine clubs from the shore; Dive Victoria Group (Queenscliff) uses it for shore-based training and guided shore dives when conditions suit; Red Boats occasionally dives the offshore boat mark.