Rungholt was a wealthy city in Nordfriesland, northern Germany. It sank beneath the waves when a storm tide (the first "grote Mandraenke") in the North Sea tore through the area on January 16, 1362.
Rungholt was situated on the island of Strand, which was rent asunder by another storm tide in 1634, and of which the islets of Pellworm, Nordstrand and Nordstrandischmoor are the only remaining fragments.
Relics of the city were being found in the Wadden Sea until the late 20th century, but shifting sediments have carried the last of these into the sea. In the 1920s and 1930s, some remains of the city were exposed; they suggest a population of at least 1500 to 2000, which is fairly large for that region and time, and it is likely that Rungholt was a major port. Legend has greatly exaggerated its size and wealth, however.