The Yonaguni Monument (Japanese: 与那国島海底地形 Hepburn: Yonaguni-jima Kaitei Chikei, lit. "Yonaguni Island Submarine Topography"), also known as "Yonaguni (Island) Submarine Ruins" (与那国(島)海底遺跡 Yonaguni(-jima) Kaitei Iseki), is a submerged rock formation off the coast of Yonaguni, the southernmost of the Ryukyu Islands, in Japan.