The Sanko Harvest is the largest shipwreck dive in Australia and is often described as the second-largest diveable wreck in the world. She was a 174 m, 32,500 DWT Japanese dry bulk carrier carrying 32,790 tonnes of phosphate fertiliser (plus about 680 t of heavy bunker fuel) when she struck a charted reef near Hood Island in the Recherche Archipelago on 14 February 1991. The subsequent inquiry blamed the master and second officer for failing to correct the ship's charts. Over the next few days the hull broke into pieces and sank, and all her fuel oil escaped; much of it washed onto the beaches of Cape Le Grand National Park, oiling seal colonies and seabirds before a clean-up in which about 80% of oiled seal pups were rescued. Salvage plans were abandoned.

The wreck now lies in about 40-44 m of water, with its highest points around 13 m. The ship split into large sections – the forward holds and the stern with its accommodation are the main pieces – and three decades of breakdown have opened the holds into a vast landscape of plates, frames and girders. Since 1995 a 500 m no-take zone has protected the site, and the steel is covered in anemones, seaweed, soft coral, sponges and ascidians. Fish life is heavy: blue groper, boarfish, bullseyes, morwong, sweep, perch, yellowtail and red snapper, with seals and dolphins sometimes appearing.

The scale is the point. A single dive covers only a small part of the wreck, and most recreational divers explore the upper hull between 13 and 30 m. The deeper parts, including the stern and bridge areas that reach the sand, are for deep-trained or technical divers.

It is a genuinely remote wreck dive – a long boat ride from a town 720 km from Perth – and weather cancels many planned trips, but for experienced divers it is one of the great temperate wreck dives in the southern hemisphere.

Esperance is about 720 km (8 hours) south-east of Perth via the Albany or Great Eastern and Coolgardie-Esperance Highways, with daily flights from Perth. Dive boats and private boats launch from the Bandy Creek Boat Harbour (5 km east of town, with ramps, parking and toilets) or operate from the town waterfront on The Esplanade. Air, nitrox and hire gear are available from Esperance Diving & Fishing on The Esplanade.

The wreck is about 21 nautical miles (39 km) from port near Hood Island in the Recherche Archipelago, roughly 10 km south of Cape Le Grand; allow 60-90 minutes each way depending on sea state. Esperance Diving & Fishing runs dedicated Sanko Harvest days (bookings essential, minimum group size) and Perth Scuba runs Esperance weekenders that include a Sanko day. Private boats must stay within the 500 m sanctuary rules and avoid anchoring into the hull.

The Recherche Archipelago lies open to the Southern Ocean, and the islands shelter each other only partly. Boat diving needs swell under about 2 m and winds under 15-20 knots; the prevailing south-westerly swell and winter cold fronts cancel many trips from May to September. Summer brings reliable morning calms but strong easterly sea breezes most afternoons.

The Sanko Harvest is one of the longest and most exposed runs from Esperance, so operators need a forecast of swell under about 2 m and moderate winds for the whole day; trips are often postponed, so allow spare days. There is usually little current on the wreck, but surface drift can develop in wind. Visibility is often 20 m or more on the wreck, better than inshore.

Descend the shotline to the highest section of the hull at 13-18 m, then work along the upper structure holding 20-30 m – for most AOW divers the plan is an exterior dive within 30 m. Explore the collapsed hold areas and hull plating, keep well clear of loose cables and plates, and return to the shot with enough gas for a safety stop. Deeper areas toward the 40-44 m sand and the stern/bridge require deep or technical training.

Nitrox (EAN28-32) recommended for the upper hull. Deep sections and the sand at 40-44 m require deep/technical training and appropriate gas; decompression dives should be planned with drifting-deco contingency. The structure is deteriorating – do not penetrate.

Operators require AOW minimum, limited to 30 m unless deep-certified.

Esperance Diving & Fishing (72 The Esplanade, Esperance; operating since 1983) – boat dives in the Recherche Archipelago on demand/weather permitting, minimum numbers apply for long trips – dedicated Sanko Harvest trips (usually two dives); Perth Scuba (Perth) – Esperance 'Sanko Harvest Weekender' trips (AOW minimum) once or twice a year; Woody Island Eco Tours references the wreck on archipelago cruises (no diving).