The Key Biscayne was a 2,695-ton steel jack-up oil rig being towed from the Arafura Sea to Fremantle when she was lost on 1 September 1983. In gale-force winds the final tow line parted, and she was last seen slipping beneath the waves at 6:45 pm. She now lies about 9 nautical miles west of Ledge Point in 42 m.

The rig settled upside down, with its jack-up legs collapsing towards the north of the platform. The shallowest point is a spud foot and the drilling platform at about 26 m, and the rest is a mass of twisted steel down to the sand at 42 m.

The wreck's reputation rests on its fish life. Grey nurse sharks frequent the northern legs, and large demersal fish, including samson fish, dhufish and schooling kingfish, are abundant. Wobbegongs rest near the spud foot, and crayfish crowd the wreckage. Visibility is often outstanding, from 10 m to 40 m.

This is a deep, exposed dive with strong currents, an hour or more offshore. Most divers do it with an operator, using a shot line and live-boat pick-ups, and the depth means short no-decompression times on air. Divingwawrecks recommends a technical decompression dive for thorough exploration.

The Key Biscayne suits experienced deep divers and technical divers, and it is one of the signature wreck dives of the Perth region.

Water temperatures on this coast range from about 17–18 °C in late winter to 22–23 °C in late summer; a 7 mm wetsuit with a hood suits most of the year.

Most trips leave from Lancelin, about 1 hour 20 minutes north of Perth via the Indian Ocean Drive. Blue Destiny, a 68 ft catamaran used by Perth Scuba, runs Key Biscayne charters from Lancelin; the run offshore takes roughly an hour, and destination guides list up to 2 hours. Private boats can launch at Lancelin or Ledge Point.

The wreck is at S 31°09.886' E 115°11.833'. Anchoring is problematic, so use a shot line and live-boat pick-up.

An open-ocean site with no shelter. Dive only in light winds, swell of 1 m or less and a reliable forecast. Strong currents flow over the site and should not be underestimated; operators drop pairs on a shot line.

Most Perth operators schedule trips from March, when the summer sea breeze eases and swell is often low. Winter fronts close the site.

Descend the shot to the spud foot and platform at about 26 m, explore the upturned platform and the collapsed legs to the north, where grey nurse sharks gather, keeping depth within plan (seabed at 42 m). Ascend the shot or a DSMB with a safety or decompression stop on the hang bar.

Nitrox 28–32% for the upper structure; trimix and staged decompression for extended bottom time at 35–42 m. Rebreathers well suited. Use a shot line and DSMB; do not anchor on the wreck.

Perth Scuba – seasonal charters aboard Blue Destiny from Lancelin (hang bars provided); Image Dive and other Perth operators run occasional trips. Most operators visit from March onwards.