St Pauls Rock is a limestone stack standing off the Sorrento ocean coast at the end of St Pauls Road, and it is one of the more atmospheric shallow dives on the back beaches because of what lies beneath it: a tunnel runs right under the rock, and the surrounding platform is riddled with what The Scuba Doctor calls mystical cave systems – small caverns, undercuts and blind holes worn into the soft rock. The depth is only 1–6 m and the kelp is thick, particularly at low tide when the fronds lie over the surface, so the dive is more a matter of weaving through gullies and ducking under ledges than of covering distance. The fauna is that of the exposed Bass Strait shallows: sweep and zebrafish schooling in the surge, old wives and magpie perch under the ledges, herring cale and wrasse in the kelp, Port Jackson sharks and draughtboard sharks resting in the caverns, abalone and the occasional rock lobster in the holes, and weedy seadragons on the kelp edge.

The tunnel under the rock is the set-piece and should be entered only when there is no discernible surge, since a set arriving while a diver is inside has nowhere to put them but the roof. As with every back-beach site, the conditions requirement is absolute: flat seas, swell under about 2 m with a long period, light northerly to north-easterly winds, usually after several days of northerlies, and an abort if there is white water on the entry. Jubilee Point 360 m to the south-east is the natural continuation for those who want more depth.

St Pauls suits experienced divers who enjoy shallow cave and gully diving and snorkellers with rough-water experience on glassy days; its parking, steep steps and exposure keep it quiet.

From Sorrento take Ocean Beach Road and turn into St Pauls Road, following it to the small car park at the end. Steps lead down to St Pauls Beach on the western side of the rock, a short but steep carry. Enter from the beach or the platform west of the rock at low tide when the reef is sheltered, and swim out to the rock and the reef around it.

Exit at the same beach. Parking is very limited.

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 from St Pauls Beach at low tide, swim out along the western side of the rock in 3–5 m and circle it, locating the tunnel that runs beneath the stack; pass through only if the surge is negligible. Continue around the outer reef to 6 m, then return to the beach on the western side.

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