Apart from the sun, the ruins and the beaches, we have other phenomena of great interest. Off the coast of the fascinating island of Santorini, or Thira as it was called, there is a live volcano. Apart from the geological interest this is a place of great physical beauty. In the first explosion of the volcano which took place circa 1450 B.C., half of the island sank in the sea, forming a "Caldera" or crevice formed by the volcanic explosions. In the middle of the caldera there are two islands which are the youngest volcanic islands in the Eastern Mediterranean. Some theories have it that Thira was the source of the myth of the lost island of Atlantis. Ecologists also were able to ask the government to declare the area around the island of Alonisos a National Sea Park of the Northern Sporades for the protection of the Mediterranean Seal "Monachus Monachus", a rare species that can only be found here.