A city dating back to 7500 bc
It found that the ruins under the sea were strung across a 9-km stretch on the banks of an ancient riverbed which even had signs of a masonry dam.
The submerged city bore striking similarities to Indus Valley Civilisation sites in the mainland.
That turned out to be the find of the 20th century.
Eleven years later, it is the turn of oceanographers from the National Institute of Ocean Technology (NIOT) in Chennai.
“When Bhirrana [Rajasthan] was excavated, from 2003 to 2006, we [recovered artifacts that provided] 19 radiometric dates,” said Dikshit, who was until recently joint director general of the Archaeological Society of India.
“Out of these 19 dates, six dates are from the early levels, and the time bracket is forming from 7500 BC to 6200 BC.” Since the early excavations at Harappa and Mohenjodaro, in what is today Pakistan, the Indus Civilization has been considered among the world's most ancient civilizations — along with Egypt and Mesopotamia (in what is today Iraq).
is multi-storey (18 storeys deep), with fresh flowing water, ventilation shafts and individually separated living quarters or 'apartments', shops, communal rooms, wells, tombs, arsenals and escape routes.
On its own it has the potential to house up to 20,000 people.
As Dikshit and his colleague, BR Mani, current joint director general of the ASI, write in a recent note on their findings: “The earliest levels at Bhirrana and Kunal yielded ceramics and antiquities ...
They did it while trawling the murky sea 30 km off the Gujarat coast in the Gulf of Cambay measuring the levels of marine pollution.
As part of the routine, they took sonar photographs of the ocean floor.
Excavation revealed 18 successive layers of buildings signifying various stages of the settlement and eras of history.
The bottom layer of buildings signifies as early as 7500 BC while the top layer is of 5600 BC.