A 600-year-old cargo ship from the Joseon Dynasty has been recovered from the seabed off the west coast of South Korea. Dubbed Mado 4, the ship sank around 1420. It is the only surviving Joseon Dynasty ship.The shipwreck was first discovered off Taean Island in 2015. National Maritime Heritage Research Institute archaeologists have been studying it ever since, recovering hundreds of artifacts including 63 wooden cargo tags with inscriptions that helpfully note the departure location and destination of the ship. The tags are inscribed Naju Gwangheungchang, meaning the ship had departed in Naju, South Jeolla, carrying the tribute and grain tax bound for Gwangheungchang in Hanyang, the government office that managed the salaries of officials, located in what is today the Mapo District of Seoul. The ships purpose was confirmed by the discovery of 152 pieces of light blue-green Buncheong stoneware, bearing the characters Naeseom, referring to the Naeseomsi, the state official responsible for managing tribute food and drink for the royal court and high-ranking officials.Grain transport ships were part of the state-run joun transport system. The cargo ships carried grain and other goods from provincial warehouses to the royal capital of Hanyang. This is the first discovery of a segok, a tax grain transport ship, previously only known from historical records of the period.The intact hull of the ship was reburied under the sand during the investigations of the past decade, but in April of this year, the National Maritime Heritage Research Institute began salvaging the hull. The operation concluded successfully last month having recovered 107 wooden components of the hull. The remaining section of hull is 39 feet long and 16 feet wide. The port side was heavily damaged when the ship capsized onto it, while the starboard side was preserved up to 11 layers high.The excavation and salvage of the vessels has shed new light on Joseon shipbuilding. It features a twin mast design unlike its Goryeo and Silla Dynasty predecessors that had a single central mast with masts installed at fore and center. This design conferred it increased sailing speed and enhanced its ability to maneuver according to wind direction. Horizontal timbers were used on the stern for increased durability and the planks on the hull were joined with wooden pegs later repaired using iron nails. These are the first metal fasteners found on a pre-modern Korean ship.The wooden components of the hull are currently undergoing desalination at the Taean Maritime Museum while a selection of artifacts is on public view. Once the salts have been removed, the timbers will be dried and stabilized, a process that will take years. Conservators will then undertake a full restoration so that the ship itself can be exhibited. The whole project is expected to take about 15 years.