Odyssey Marine Exploration was, in 2007, one of the most aggressive deep-water salvage companies in the world. Founded in Tampa, publicly traded, and equipped with remotely operated submarines that could work at depths far beyond traditional divers, Odyssey treated the seabed of the Atlantic as a vast unmapped archive of cargoes and coins waiting to be retrieved. The Black Swan find was their masterpiece. Coin expert Nick Bruyer, who examined a sample of 6,000 of the recovered coins, told reporters, 'For this colonial era, I think this find is unprecedented. I don't know of anything equal or comparable to it.' Odyssey predicted the wreck would become one of 'the most publicised in history'. What the company would not say was where the wreck actually lay. The Merchant Royal rumour was useful cover. By keeping the location and identity vague, Odyssey hoped to retain salvage rights under American admiralty law - the legal tradition that historically rewarded finders who recovered cargo from the seabed. Spain, watching the Gibraltar airport video of crates being loaded onto a Boeing 757 chartered for Florida, was not convinced.

The ship Odyssey had found was the Nuestra Señora de las Mercedes, a Spanish frigate sunk by the British Royal Navy off Portugal in 1804. The encounter happened during a peacetime pursuit that Spain regarded - then and now - as an act of unprovoked aggression. The Mercedes was carrying coins minted in Spanish colonial America, much of it from Lima, the silver and gold of an empire whose extractive machinery had ground for three centuries. Behind every coin in the cargo lay a story of forced labour in the South American silver mines - Potosí, Lima, Cerro de Pasco - where indigenous and African workers died in extraordinary numbers to fill Spanish treasuries. The Mercedes was the ship that was supposed to bring the latest such cargo home. Two hundred and fifty Spanish sailors went down with her. When their descendants and the modern Spanish government heard that an American company was suddenly flying seventeen tons of those coins out of Gibraltar in unmarked crates, the response was not subtle. Spain sued. So did Peru, claiming the Lima-minted coins on grounds of cultural patrimony. Descendants of merchants whose private cargo had been aboard the Mercedes also joined the litigation.

The case wound through American federal courts for five years. Odyssey argued the wreck was found in international waters and that admiralty law gave them rights to the recovery. Spain argued that the Mercedes was a Spanish naval vessel and that the doctrine of sovereign immunity, recognised in the Foreign Sovereign Immunities Act, applied to the ship and to everything she had been carrying. On 4 June 2009, a US magistrate judge in Tampa ruled in Spain's favour. On 22 December 2009, a district judge confirmed the ruling, writing 'the ineffable truth of this case is that the Mercedes is a naval vessel of Spain and that the wreck of this naval vessel, the vessel's cargo, and any human remains are the natural and legal patrimony of Spain'. In September 2011, the 11th Circuit Court of Appeals agreed. Odyssey filed an emergency stay with the Supreme Court. On 9 February 2012, Justice Clarence Thomas denied it without comment. On 24 February 2012, two C-130 Hercules aircraft of the Spanish Air Force collected the treasure in Florida and flew it home. In May 2012, the Supreme Court declined to take up the case at all.

On 2 December 2012 the Spanish government deposited 14.5 tons of recovered coins in the National Museum of Subaquatic Archaeology in Cartagena, in the Region of Murcia, where Spanish law dictates they can never be sold. They are catalogued, studied, and displayed - patrimony rather than profit. In 2015 a US district court ordered Odyssey to pay Spain $1 million for 'bad faith and abusive litigation', the judge noting that Odyssey 'knew at all times that Spain, given the information pertinent to identification, possessed the historical information and the expertise to identify immediately whether the wreck in question was a Spanish vessel' - and that Odyssey had never asked. The case has since become a precedent that reshaped the entire field. Underwater archaeology has moved decisively toward national sovereignty and away from commercial salvage; UNESCO's 2001 Convention on the Protection of the Underwater Cultural Heritage has gained signatories partly on the strength of the Black Swan precedent. A 2018 graphic novel, The Treasure of the Black Swan, was adapted into the Spanish television series La Fortuna in 2021. National Geographic's 2021 documentary Battle for the Black Swan won a gold medal at the New York Festivals. A small note in the official Spanish ministry literature observes that some of the cannon on the Mercedes had been cast in bronze and signed by the smelter Bernardino de Tejeda, born in Seville, who died in Lima - the direct ancestor of Javier Pérez de Cuéllar, the Peruvian diplomat who served as fifth Secretary-General of the United Nations from 1982 to 1991. The coins have come home. So, in a way, has the story.