by a final flood between 1998 and 1999. Ferdinandea, submerged volcanic island which has appeared at least four times in the past. Ravenser Odd, a large 13th-century town on an old sandbank promontory in East Yorkshire, which became an island and then vanished in January 1392. Dadu Island, which was legally the southernmost point of the United States of America, located at Palmyra Atoll (an incorporated U.S. territory) and still shown on the map, was a bare sand islet washed away by a storm in 2014. (It was named after a dog, "Dadu", that had lived at the atoll.) Semyonovsky Island, an island that was discovered in 1770, it had rapidly decreased in size, to 1823, in 1936, by the 1950s it was just baydzharakh and when visited in the early 1960s it had been submerged due to erosion. Balkanatolia, a sunken land in the Mediterranean Sea. Lost continents Greater Adria, a continent connecting between Italy and North Africa. Zealandia, a scientifically accepted continent that is now 94% submerged under the Pacific Ocean, surrounding the areas of New Zealand and New Caledonia. Mythological lands Agartha, in the Hollow Earth. Atlantis, Plato's utopian paradise. Avalon, the mythical lost land or island in Arthurian, Cornish and Welsh legend. Buyan, an island with the ability to appear and disappear in Slavic mythology. Cantre'r Gwaelod, in Welsh legend, the ancient sunken realm said to have occupied a tract of fertile land lying between Ramsey Island and Bardsey Island in what is now Cardigan Bay to the west of Wales. Iram of the Pillars, a reference to a lost city, country or area mentioned in the Qur'an. Jomsborg and Vineta, legendary cities on the south coast of the Baltic Sea supposed to have been submerged in the Middle Ages. Kitezh, a legendary underwater city located in Russia, populated by spiritual people. Kumari Kandam, a mythical lost continent with an ancient Tamil civilization in the Indian Ocean Lemuria, a mythical lost continent in the Indian or the Pacific Ocean. Llys Helig Welsh legends regarding the local rock formations conceal the palace of Prince Helig ap Glanawg, said to be part of a larger drowned kingdom near Penmaenmawr, Wales. Lyonesse in Arthurian literature: it was the home of Tristan and is usually associated with the Isles of Scilly, Cornwall (an area inundated by the sea c.2500BC). The tale parallels the Welsh and particularly Breton legendary lost lands.