Poompuhar, a celebrated port town of Sangam period (300 BC to 400 AD) was the capital of famous Chola dynasty during early centuries of Christian Era. Onshore explorations brought to light a few brick structures and terracotta ring wells, besides a few early Chola period coins. Two brick structures and a few ring wells were also noticed in inter tidal zone. Offshore explorations have been carried for three seasons along the Poompuhar coast from inter tidal zone to 25 m water depths. Geophysical explorations have indicated various features between 5 to 10 m waters and 19 m and 23 m water depths. Diving operation in these brought to light a habitational remains opposite to the river Kaveri mouth and north of Poompuhar. A large number rolled pottery of historical period was also noticed. The stone structure in 23 m water depth is in U-shape and in front of this there are two small structures were also noticed. A detail discussion on the nature of these structures and uses have been discussed. A ship wreck also noticed in 19 m water depth where a large number of lead ingots were found.