Phelan Bluff is the eroded basalt cliff on the south side of Phillip Island's Summerland Peninsula, named for Pat Phelan, an Irish settler who worked for the McHaffie family, the island's first pastoralists. The reef below it is one of two boat-only sites Scuba Doctor lists along this closed stretch of coast. The description is precise: the area transitions into basalt reef with large stone blocks along the eroded cliffs; shallow channels and gullies near shore contain rounded boulders and extensive kelp beds; and the safer diving occurs in the offshore reef zone, where water clarity is superior and marine life more diverse.

That gives the dive its shape. Inshore, at 2–6 m, is a zone of wave-rounded boulders and dense kelp in narrow channels – attractive on a flat day but surgy and unforgiving in any swell. Further out, at 8–12 m, the cliff-fall blocks stand on a sand and cobble floor with ledges and overhangs between them, and here the kelp thins and gives way to sponge, zoanthid and ascidian cover, with crayfish and abalone in the cracks, resting Port Jackson and draughtboard sharks, blue devils and bullseyes under the overhangs, and morwong, sweep, wrasse, boarfish and old wives over the reef, as at the neighbouring shore sites.

Fur seals from Seal Rocks patrol this coast. Like Mandeville Road a kilometre west, Phelan Bluff has no shore access – the peninsula is a penguin reserve closed to off-track walking – and its exposure to Bass Strait means it is dived only from private boats on the calmest northerly days, usually as part of a run along the south coast from Newhaven or around The Nobbies from Cowes. It is a scenic, shallow, high-relief basalt reef beneath dramatic cliffs and, for experienced boat divers with the right weather, a chance to dive coastline almost nobody visits.

Boat access only, as for Mandeville Road: launch at Cowes or Rhyll and run west around The Nobbies (crossing the Seal Rocks passage near slack), then east along the south coast to the bluff – roughly 14 km and 30–40 minutes from Cowes – or run west from Newhaven along the entire south coast. Anchor in sand off the outer reef in 10–12 m rather than among the inshore boulders. Land access across the Summerland Peninsula is closed to protect penguin burrows.

A high energy open sea zone on the exposed south coast; best with calm seas and offshore northerly winds at high tide, and only after a run of settled days with swell under 1 m. Southerly and south-westerly swell breaks over the inshore boulders and makes the whole site surgy. The boat passage around The Nobbies is tide-limited.

Late summer and autumn offer the most windows; effectively a fair-weather-only site.

Descend the anchor line onto the offshore reef zone at 8–12 m, where Scuba Doctor notes the safer diving and better clarity, and work along the outer reef parallel to the cliff with the shore on one side. Look into the ledges under the large basalt blocks, turn at half gas, and return at a slightly shallower level through the edge of the kelp, staying out of the inshore channels if there is any surge. Safety stop on the anchor line.

No regular operator – private boats and Melbourne club boats on rare calm days only.