Pecio de San Andrés

The route follows the island's cliff south, and where the cliff ends you leave the rock and descend perpendicular to it onto a slope where sand and boulders alternate. The boat needs under ten minutes from the harbour. The iron starts at about 22 m and runs down the slope to a lone boiler at about 39 m, which marks the end of the ship. Leon Marino starts instead from a descent line laid by the park, with its foot at 14 m.

The timber is gone, so nothing reads as a hull. You are over what was the hold, among the iron frame of the engine bed and the machinery it carried, with a paddle wheel on each side: the port wheel well preserved, the starboard wheel destroyed. Hovering above the axle gives the clearest view of the whole structure. Debris spreads about 100 m around, and a torch brings out the yellow and orange of the growth on the metal. Some guides start at a large iron arc taken for part of the old stern.

A guided dive spends about 30 minutes on the wreck, then follows the rising bottom back toward the island. Some dives finish in the small cave of El Boquete, about 6 m down near the San Andrés mooring buoy.

With the hull lost and the machinery standing, this is a wreck you read by its engineering: two paddle wheels, the engine bed between them and the boiler at the far end, all under orange Astroides coral and ascidians. The iron is the Don Juan, a British mail steamer lost in 1837; the San Andrés name comes from lead ingots stamped with it that divers raised from the debris.

At least four conger eels keep home caves in the metal, and moray eels and octopus use the gaps. Clouds of swallowtail seaperch hang over the structure, with bogue above them.

Sunfish come in when the tide strengthens, sometimes up to fifteen together, and the wreck works as a cleaning station. Loggerhead turtles pass in the summer months.

The Don Juan was a wooden paddle steamer of 932 tons, 45.2 m long, with a 360 hp direct-acting engine, built in 1837 for the Peninsular Steam Navigation Company, the line that became P&O. She sailed from London on 1 September 1837 on her first mail voyage for the company, with its founder Arthur Anderson aboard. On 15 September, returning from Gibraltar in thick fog, she ran onto the reefs at Punta Marroquí, off Isla de Tarifa, and was lost. Salvage failed.

For decades the wreck was given as the Miño, an iron screw steamer lost in a collision with the frigate Minden in 1856. A 2019 journal article concludes that the remains are the Don Juan and not the Miño.1 The wreck is a wooden paddle steamer and the Miño had an iron hull and a screw. The lead ingots match the 21 tonnes of lead the Don Juan carried. The Miño went down about three miles off Punta Carnero, nearer Algeciras, so her wreck should lie near Ensenada del Tolmo. Some local centres still tell the Miño story and others have taken up the Don Juan.

Divers also recovered English soda-water bottles, which fit a British ship.

Plan gas and no-stop time for the 28 to 30 m working level. Leon Marino lists nitrox, a torch and a surface buoy as extras for this dive, and the torch earns its place in the conger caves and on the growth.

The dive is almost always possible, except at the start of the flood and in strong levante storms. Once the flood is running the boat anchors at the Marroquí, and on the ebb at the El Agujero platform, so the current is against you on the swim in. It runs from none to very strong depending on the day, and that approach is the part of the dive to plan around.