The Willyama was one of the finest colliers on the Australian coast in her day. Built in 1897 at Newcastle-upon-Tyne, she was a steel, schooner-rigged screw steamer of 2,705 tons and about 99 m (325 ft) long. On 13 April 1907, running from Newcastle NSW towards Port Pirie, she struck the limestone reef off Rhino Head in Marion Bay after her master mistook his position – the Marine Life Society records that he believed he was off Kangaroo Island rather than Yorke Peninsula.

She could not be refloated and broke up where she lay. Today the wreck is fairly broken up and scattered over the reef in 1-12 m, but the major pieces are impressive. The sternpost and steering quadrant still stand at or just above the surface at low water, and the SDFSA notes one of her masts once protruded a couple of metres out of the water.

The boilers, engine, sections of hull plating and a long propeller-shaft inspection tunnel running forward from the stern give plenty to explore, and the steel has become a reef dense with fish: sweep, old wives, magpie perch, zebrafish, leatherjackets and schools of trevally, with blue groper and crayfish in the gutters. The shallowness and moderate depth make it technically easy, but currents around Rhino Head and the swim from shore make it more demanding than it looks; most divers visit by boat as a second dive or tank-finisher, combining it with Rhino Head's limestone reefs nearby. The Willyama is part of the Investigator Strait Shipwreck Trail and is protected.

It suits Open Water divers comfortable in some current, and snorkellers can see the upper wreckage on calm days.

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). Launch at the Marion Bay boat ramp and run a few minutes west along the bay to Pelican Point and Rhino Head; the wreck lies roughly 160 m offshore (DEW) with scattered wreckage extending further, and the sternpost breaks the surface at low tide, making it easy to find. A shore swim from the point is possible but involves a long surface swim in full gear across current-affected water, so most divers treat it as a boat dive to finish a tank.

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 Willyama is inside Marion Bay and somewhat sheltered from westerly swell, but currents around Rhino Head can be strong.

Anchor near the stern, where the sternpost and quadrant break the surface, then follow the propeller-shaft tunnel and scattered plating forward along the reef, exploring the boilers and engine. Return along the other side of the debris field to the stern.

No resident charter at Marion Bay; dived by Adelaide shops and clubs on Innes/Marion Bay boat weekends and by private boats from the Marion Bay ramp.