Off the coast of Japan’s Yonaguni Island lies a submerged enigma: massive stone terraces, staircases, and pyramid-like structures stretching 165 feet long and 65 feet wide.

Discovered in 1986, the Yonaguni Monument has sparked a fierce debate. Some researchers claim it’s a man-made relic of a mythical lost civilization, pointing to tool marks and carvings resembling animals and human faces.

Skeptics argue it’s a natural formation shaped by earthquakes and currents—though even they admit its 90-degree angles and symmetrical platforms are uncanny. Estimated to be 10,000–16,000 years old, this ‘underwater city’ could rewrite history—if proven artificial.

Dive into the clash of science and myth, and decide: ancient engineering marvel or Earth’s jaw-dropping geology?