Diving in the transparent waters of the Florida Keys is a unique experience. On the white-sand bottom sea stars crawl the surface and spider fish stalk their prey. Not far, about 10 miles to the east of the Marquesas Keys, the sea floor is also populated by rounded balls, covered in corals and molluscs. What natural phenomena could have created them? None, these are iron cannon balls from the Spanish galleon “Nuestra Señora de Atocha” (1). Transporting a rich cargo of silver, gold, pearls, emeralds, indigo, tobacco and even ivory from Sri Lanka, was struck by a hurricane and sunk in 1622 and sunk. The “Atocha” is not alone, UNESCO has estimated that 3 million vessels ever to ply the seas lie wrecked at the bottom (2). Many of their names have found their way into popular books and films, the Vasa capsized in front of Stockholm in 1628, the Titanic hit an iceberg in 1912, the Lusitania was torpedoed in 1915, the Yamato was bombed in 1945, and the Kursk lost to an explosion in 2000; but many other just appear briefly in the pages of the papers or are never reported. Given our advance satellite technology, weather forecast models and relative war-free oceans, why do ships still sink? There are many reasons. Despite our understanding of the weather, the sea can be unpredictable. Hurricanes, typhoons and cyclones are a major cause, but also less known phenomena such as rogue waves popularised by the book and film “The Perfect Storm”. These are random surface waves that form in open waters and can reach up to 30 metres in height. They are documented to have damaged and sank ships of every size, including the supertanker MS München in 1978 (3). However, human factors are most often responsible. Ferries, particularly those unfit for purpose or overcrowded, have caused many fatalities in Africa and Asia, for example the sinking of the Zico in Mozambique in 2022. The tragedies of small boats carrying migrants in the Andaman Sea, the Mediterranean Sea, and the English Channel keep on featuring on the pages of newspapers. Then, there are fires on board, electric problems, structure hull failures, poor maintenance, unproper loading, and collisions with other vessels, harbours or the coast (4). In most cases these could have been avoided by following the strict navigation safety protocols. Reviewing images of Roman amphora littering the entrance to the port of Fiskardo in Kefalonia, one can only imagine how it must have been to sail in ancient times, trading metals and wine from Cádiz to Tiro, defying storms, reefs and pirates (5). Nowadays, most ships are directed electronically from far away bases, hence the high seas have never been busier or safer. Yet, one truth remains, there is no unsinkable ship. Photo: Shipwreck of the SS American Star on the shore of Fuerteventura by Wollex Read more: 1) https://maritime-executive.com/editorials/the-world-s-most-valuable-shipwreck-the-nuestra-senora-de-atocha 2) https://unesdoc.unesco.org/ark:/48223/pf0000152883 3) https://www.glerl.noaa.gov//pubs/fulltext/2007/20070019.pdf 4) https://www.cruisehive.com/how-many-cruise-ships-have-sunk/117798 5) https://edition.cnn.com/travel/article/roman-shipwreck-kefalonia-fiskardo/index.html