Cape Schanck is the basalt headland at the southern extremity of the Mornington Peninsula, capped by an 1859 lighthouse and fronted by Pulpit Rock, the columnar stack at its tip, and its western side is the most spectacular shore dive on the peninsula's ocean coast. The Scuba Doctor lists it at 1–7 m for Advanced divers and describes a dive that swims around the cape in the channel between the headland and Pulpit Rock into a western shore of big gullies, gorges and bommies on a rocky bottom, with two named features: The Arch, an underwater cave through the rock, and Shark Cave, a cavern that is usually occupied by Port Jackson sharks. Because the cape is volcanic rather than limestone the rock is hard and dark, the walls are vertical and the gullies deep, and the life is correspondingly dense – sponges, sea tulips and lace corals (bryozoans) on every shaded face, kelp on the ridges, schools of sweep and zebrafish in the surge, old wives, boarfish, magpie perch and wrasse in the gorges, rock lobsters and abalone in the cracks, and weedy seadragons on the kelp.

Further out, reefs at 15–25 m of rubble, bedrock, sand and kelp gardens rise to deeper pinnacles covered in colourful sponges and corals; these are boat dives and the Cape Schanck Cray Reef north-west of the lighthouse is the best known. The source is unequivocal that the shore dive can only be done in very calm conditions and is unsafe in any swell: Cape Schanck takes the full force of Bass Strait, the channel becomes a rip on a falling tide, and the nearly kilometre-long walk and 100 m climb with gear mean a diver is committed long before reaching the water. On the rare glassy days, however, it is unforgettable.

It suits experienced, fit Advanced divers with surf skills, and it rewards a guide who knows the caves.

Drive to the Cape Schanck lighthouse car park at the end of Cape Schanck Road (Mornington Peninsula National Park, parking fees may apply). Follow the boardwalk and the long staircase down toward Pulpit Rock – nearly a kilometre of walking from the car park and about 100 m of descent, all of which must be climbed back with wet gear; a second trip for tanks is normal. Enter from the rock platform on the western side beside Pulpit Rock in the sheltered channel at low tide.

Exit by the same route. Boats from Flinders (15 km east) dive the offshore reefs.

The back beaches face south-west into Bass Strait and are safe to dive only in rare flat conditions: The Scuba Doctor's rule of thumb is swell under about 1.5–2 m with periods of 10 seconds or more, usually only after three or four days of northerly to north-easterly winds, with light northerly winds on the day. Any southerly or westerly wind, or a fresh swell, makes the entries lethal. Dive around low tide when the limestone platforms are exposed and the gullies are sheltered, and abort if there is white water over the entry.

Rips and tidal streams near The Rip run even on calm days, and conditions change within an hour. Winter high-pressure systems bring the calmest spells; summer sea breezes rule out afternoons.

Enter the channel between the cape and Pulpit Rock at low tide, swim around the cape on the western side through the big gullies and past the bommies in 4–7 m, locating The Arch and Shark Cave, then turn at half gas and return through the channel; the offshore reefs at 15–25 m are a boat dive, not a swim.

No regular operator. The Scuba Doctor (Rye) and Peninsula clubs run occasional guided shore dives when conditions allow; otherwise experienced private groups only.