The Nuestra Senora de las Mercedes

The Nuestra Señora de las Mercedes was a frigate belonging to the Spanish Armada, which was launched at the port of Havana 1786 and was part of the convoy that covered the trade route between the American colonies and Spain. On 5 October 1804 at the Battle of Cape Santa Maria, Nuestra Señora de las Mercedes, commanded by José Manuel de Goicoa and Labart, was sunk in waters near the Strait of Gibraltar.

While sailing back from South America with more than 200 people on board, the ship was intercepted by British ships. Spain was a neutral country at the time, but had been showing signs of declaring war in alliance with Napoleonic France. The galleon was ordered to change course towards England, but its senior Spanish officer refused and opened fire on the British. Tales recount that the Mercedes broke 'like an egg, dumping her yolk into the deep'. After the attack most of the survivors were rescued from one or two small boats. The English Prize Office removed 4,773,153 gold and silver pesos from three captured ships, 1,307,634 of which belonged to the king of Spain. After the incident, Spain declared war on England.

In late 2012 a treasure haul was salvaged and displayed. The loot had been at the center of a five-year legal battle between a U.S. salvage company and Spain. US firm Odyssey Marine Exploration found the lost treasure off Portugal's Atlantic coast in 2007. At the time, the treasure was estimated to be worth $500m (£316m).

International treaties generally hold that warships sunk in battle are protected from treasure seekers. Odyssey lost every round in federal courts as the Spanish government painted the company as modern-day pirates. The company has said in earnings statements that it has spent $2.6 million salvaging, transporting, storing and conserving the treasure.