The Yonaguni Monument is an underwater rock formation located off the coast of Yonaguni, a small island in Japan. Discovered in the 1980s, it features large, flat terraces and straight edges that some believe resemble ancient structures. The site has sparked debate among researchers regarding its origins, with theories ranging from natural geological processes to the possibility of human-made structures. Diving at the Yonaguni Monument attracts both tourists and archaeologists, eager to explore its unique features. The site is often associated with the idea of a lost civilization, drawing comparisons to other ancient sites like Atlantis. However, definitive evidence supporting these claims remains elusive.