Stenhouse Bay was once a busy gypsum port: from 1913 until the 1930s gypsum mined around Inneston and Lake Stenhouse was railed to the bay and loaded onto ketches and steamers from this jetty. The mine town is now part of Dhilba Guuranda-Innes National Park, and the jetty is one of the best and most unusual jetty dives in South Australia. The piles stand in about 8-10 m of clear, oceanic-influenced water, and their growth is quite different from the gulf jetties.

The Dive Shack highlights basket stars, gorgonians and other marine life not common around the peninsula, and visitor information adds leafy seadragons and boxfish. Sponges, soft corals and ascidians coat the timber, and the SDFSA describes amazing life on the numerous pylons. Magpie perch, old wives, zebrafish, sweep and leatherjackets school under the deck, blue groper visit, and a low reef under the outer end adds crevices for crayfish and octopus.

Two oddities add interest: an upside-down Ford Telstar sitting on the bottom at the end of the jetty, and, just to the east, the hull of the four-masted barque Hougomont, scuttled in 1933 as a breakwater. Many divers do both on one tank. The catch is the entry.

Access is down a steep path and a ladder, which is hard work with twin tanks or a heavy rig and dangerous in surge. Visitor information recommends it for advanced divers only, attempted in minimal swell. On a calm day, though, it offers clear water, rare invertebrates and a historic wreck, all from shore.

From Adelaide drive about 300 km (3.5 hours) via Port Wakefield, Minlaton and Warooka to Marion Bay; Dhilba Guuranda-Innes National Park begins just west of the township (vehicle entry fee, pay online or at the Stenhouse Bay visitor centre). Stenhouse Bay is 5 km inside the park from Marion Bay; park in the jetty car park near the visitor centre. The walk down to the jetty is steep and the only entry is by ladder, so rig carefully and consider lowering heavy gear.

Swim out under the jetty towards the end, where depths reach about 10 m. Boats can come around from the Marion Bay ramp in about 10 minutes.

The southern tip of Yorke Peninsula faces the open Southern Ocean and Investigator Strait, so south-westerly and southerly swell is the controlling factor: most exposed sites need swell under about 1.5 m and are best after several days of northerly or north-easterly winds, which blow offshore along this coast. Winter cold fronts bring big south-westerly swell and strong winds and can close the area for days. Summer afternoon south-easterly sea breezes make boat runs rough, so launch early.

Visibility is typically 10-20 m in settled conditions but drops sharply with swell-driven surge. The jetty is only diveable when swell is minimal – surge under the piles and on the ladder becomes dangerous in any southerly swell.

Enter by the ladder, descend along the piles and work out to the end at 9-10 m to see the upturned Ford Telstar and the low reef under the outer jetty, then cross east to the Hougomont before returning to the ladder.

No resident operator; dived by Adelaide shops and clubs on Innes trips and by independent divers. Visitor information recommends it for advanced divers only in minimal swell.