When the shoreline receded during the 2004 tsunami, tourists in Mamallapuram swore they saw a long row of granite boulders emerge from the sea, before it was swallowed again as the water hurtled forward. More than a decade later, a team of scientists and divers have uncovered what eyewitnesses saw on that fateful day - vestiges of an ancient port. In a discovery that could lead to more underwater explorations off the historic town of Mamallapuram, a group from National Institute of Oceanography (NIO) has found the remains of a port or ruins of one of the six shore temples which, according to legend, went underwater. The 10-member team, comprising divers, geologists and archaeologists, found a 10m-long wall, a short flight of stairs, and chiselled stone blocks scattered on the seabed. They were found 800m from the shoreline at a depth of nearly 27ft.

However, the team wasn't equipped to take underwater images. Historians say many of these structures, including the port, could have gone under water because of a tsunami-like event that took place in 952 AD.

Geophysical survey data from past explorations also confirm the submergence of a large area comprising a building complex, which, they say could be possible remains of a submerged township.

A global sea level rise of even 1-2mm per year would inundate up to several hundred metres of coast line over a period of 2,000 years. Other reasons for submergence of these structures could be soil erosion and tectonic movement.