Poompuhar

The shore temple at Mahabalipuram survived the tsunami this time. Apparently there were six other temples and they were all swallowed by the sea. It seems the ancient Tamil city of Poompuhar was also taken by the sea about 1500 years back.

Poompuhar was the capital of the Chola rulers, a Tamil dynasty with a recorded history going back to the second century B.C. It was a place where silk merchants and grain traders set sail for the Far East, Greece and Egypt, archaeologists say.
The town had special enclaves for foreign visitors and the king’s soldiers. In the streets, languages could be heard from around the world. It was dotted with temples, a sign of a prosperous Hindu kingdom.
But the ancient city now lies under water about three kilometers (two miles) offshore. All that remains are a few temples and the modern town, which consists of about 2,000 fishing families.
Undersea excavations and studies by historians show that Poompuhar grew into a big town during the reign of Karikal Cholan, the second-century Chola king who established trade ties with China, Arabia and the Roman Empire.
Remnants of brick buildings, water reservoirs, a boat jetty and Roman coins have been found during undersea excavations. [Was ancient Indian town swallowed by tsunami?]

Some marine archaeology was done at Poompuhar or more correctly at Kaveripoompattinam as the ancient city was known. Evidence was found that it was a big port during 3rd century BC. Due to lack to funds archaeology in this area was stopped.
Related Link: More on Dwaraka