Marine archaeologists working off the coast of Okinawa, Japan, have announced the discovery of what appears to be a vast submerged city nearly 30 meters beneath the Pacific Ocean.

The underwater site features massive stone terraces, wide staircases, and carved monoliths arranged in geometric formations. Researchers say the scale and structural complexity suggest deliberate construction rather than purely natural rock formations. Divers have documented stepped platforms, flat plazas, and vertical stone walls that resemble architectural planning.

Some experts involved in the preliminary assessment estimate the site could date back as far as 12,000 years — placing it at the end of the last Ice Age. If confirmed, such a timeline would significantly challenge current understanding of early urban development in East Asia, where established models suggest large-scale urbanization occurred thousands of years later.

The discovery site lies near Okinawa, within a region already known for unusual underwater rock formations. However, archaeologists argue that certain carvings and structural alignments point toward human modification.

Further investigations are underway, including sediment analysis, 3D seabed mapping, and material sampling. Researchers caution that additional evidence will be required to confirm whether the formation represents a lost prehistoric city or an extraordinary natural geological phenomenon.

If proven to be man-made, the find could reshape discussions about early seafaring cultures and coastal civilizations at the close of the Ice Age — a period when rising sea levels submerged vast areas of land across the globe.