The St Paul is the deepest and most serious of the Smith Rock wrecks. She was a steel single-screw steamer of 1,660 tons, about 230 ft long, built in France in 1912. On her last voyage she was carrying 2,800 tons of chrome ore from New Caledonia when she struck Smith Rock in 1914 and sank, with the loss of 18 lives including her captain.

She came to rest about 1,000 m east of the rock on a gentle sand slope in 38-43 m. After more than a century the superstructure has largely collapsed, but the heavy components remain clearly identifiable: the twin boilers, the engine, winches, the propeller and an anchor. Twisted handrails and parts of the superstructure lie among the debris.

The wreck is well covered in sponges and corals, and it attracts pelagic and reef fish, rays, octopus, wobbegongs and large estuary cod. With the right conditions, visibility of 20-30 m lets divers see much of the site from the shot line. Depth is the defining factor.

On air, UniDive estimates only about 8 minutes of no-decompression time, and it recommends the wreck only for very experienced divers operating near recreational limits. Currents of up to 2 knots mean the dive must be timed for slack water, and in practice it is best done by technical divers using appropriate gas and a planned decompression schedule rather than as a squeezed no-stop dive. For those equipped for it, the St Paul is one of the more significant deep wrecks within reach of Brisbane.

Boat access only. Brisbane charters leave from Manly Boat Harbour (Brisbane Scuba departs from the corner of Royal Esplanade and Davenport Drive, Manly) or from Scarborough Boat Harbour on the Redcliffe Peninsula, crossing Moreton Bay and running out through the North West Channel past Bulwer and Comboyuro Point to the northern tip of Moreton Island. Allow roughly 75-90 minutes from Manly in good conditions.

Sunshine Coast operators run south from The Wharf, Mooloolaba, in about 45 minutes. Private boats typically launch at Scarborough or Bribie Island; the open-water crossing around Cape Moreton is exposed and should only be attempted in settled weather with local knowledge. Smith Rock lies between Cape Moreton and Flinders Reef, a short run from the cape; the three historic wrecks lie on and around it.

The St Paul lies about 1,000 m east of the rock in deep water; operators drop a shot at slack water.

Up to 2-knot currents run across the site, so the St Paul can only be dived at slack water, and the window is short for a deep dive with a long ascent. Needs calm seas (swell under about 1.5 m, light winds) so the boat can hold station and recover divers drifting on their ascent. Visibility averages 15-30 m, best in winter.

Descend the shot at slack water directly to the boilers and engine at about 38-40 m, look at the winches, propeller and anchor, and leave the bottom on time. Ascend the shot line or a DSMB with staged safety or decompression stops.

Best dived with trimix or at minimum well-planned air/nitrox decompression; carry a DSMB and redundant gas; nitrox or oxygen for deco stops. Shot line recommended.

No regular schedule; dived occasionally by experienced club groups (UniDive, Brisbane Sub-Aqua Club) and by charter (Supercat Charters) for deep-certified divers at slack water.