On 4 August 1845 the emigrant ship Cataraqui, bound from Liverpool for Melbourne with 366 passengers and a crew of 43, struck the reef off King Island's south-west coast in a storm at night. The captain believed he was approaching Port Phillip. The Marine Life Network guide recounts how the ship struck the offshore reef at about seven knots, was forced over it, struck several more times and stuck fast about 100 m from shore; passengers and crew were swept from the decks through the night until she broke in two. Only eight crew and one passenger survived, making it Australia's worst civil disaster.

Under water, the guide rates the site 6 out of 10 at 4-7 m: an exposed reef where the wreck has broken up in the shallows, with an anchor and capstan clearly visible and a few artefacts - iron concretions, lead sheeting and pieces of slate - wedged in cracks. Numerous crayfish and schools of fish live on the reef. An account of recovered relics records that divers removed two cannon, an anchor and other items in 1975, and the guide notes the anchors corroded without conservation, a cautionary tale for wreck divers.

King Island has more recorded shipwrecks than anywhere else in Australia - King Island Tourism puts the figure at over sixty - because ships running for Bass Strait on the 'clipper route' from Europe had to thread the gap between the island and Cape Otway, often in fog and gales with uncertain navigation. Most wrecks lie in shallow water on exposed reefs and have been broken up by more than a century of westerly swell, so diving them is about history and scattered remains rather than intact hulls.

All wrecks over 75 years old are protected under Commonwealth and Tasmanian heritage law: look but do not touch, and report any new finds to the Parks and Wildlife Service maritime archaeologist. With no chamber on the island, a diving injury means aeromedical evacuation to Melbourne or Hobart, so dive conservatively and carry oxygen.

King Island is reached by air from Melbourne (about 50 minutes), Burnie/Wynyard or Launceston; there is no passenger ferry, so divers fly in and hire a vehicle at the airport near Currie. Currie, the main town, is on the west coast; Grassy (with its harbour and boat ramp) is on the south-east coast about 30 minutes' drive away. Roads to the coast are a mix of sealed and gravel.

The Cataraqui memorial (bell, plaques and graves) is on Pearsons Lane, Pearshape, on the south-west coast, reached by an unsealed road for which a higher-clearance vehicle is recommended. The wreck site is on the offshore reef and is a boat dive; the nearest ramps are at Currie or Grassy, and the run down the exposed west coast needs a flat sea.

King Island sits in the path of the Roaring Forties, and its west coast (Currie, Netherby, Cataraqui, Brahmin) takes the full force of the prevailing westerly and south-westerly swell; these sites are diveable only after long calm periods or in easterly weather, which is most common in late summer. The east coast around Grassy is sheltered in westerlies and becomes the fallback. Strong tidal streams run around the island's capes after gales.

The Cataraqui reef is among the most exposed places on the island and is rarely diveable.

In a flat sea, anchor off the reef and dive the shallow gutters looking for the anchor, capstan and concretions wedged in cracks. Keep the dive short and stay well clear of the breaking reef edge. Turn the dive at half gas (thirds where current or overhead sections are involved), deploy an SMB before surfacing for the live-boat pick-up, and complete a 3-minute safety stop at about 5 m where depth allows.

No dive shop or charter currently listed on King Island (Underwater Australasia has no listings); the King Island Dive Charters/Dive Centre referred to in older guides no longer appears to trade. Visitors must bring their own gear and arrange cylinders and a boat locally (hire weights/tanks on the island where possible to reduce air freight). Verify any current operator before travelling.