Marine archaeologists using high-resolution multibeam sonar have identified a massive submerged stone structure off the coast of Vietnam, believed to be a ceremonial causeway from the Dong Son culture. The structure spans nearly 300 meters and is located ten meters below the current sea level, suggesting it was once part of a coastal ritual center before being claimed by rising tides in the late Bronze Age.
Preliminary diver surveys have recovered fragments of geometric pottery and small bronze bells embedded in the silt surrounding the stone slabs. This finding provides critical evidence of how ancient maritime communities in Southeast Asia adapted to changing shorelines. The causeway's alignment suggests it may have been used for solar observations or as a processional path for water-deity festivals that characterized the pre-imperial civilizations of the Tonkin Gulf.