The protestors also raised black flags inside the sea.
The protestors say they are ready to die for stopping the Kudankulam plant's operations.
The protestors have threatened to protest in water every day.
Coastguards were carrying out an aerial surveillance in the area.
Hundreds of villagers entered the sea protesting against the loading of fuel in the Kudankulam Nuclear Plant reactors.
There was less police presence in the are where hundreds of villagers entered the sea.
Earlier on Wednesday, fierce clashes took place between the police and protestors while villagers accused securitymen of looting and destroying their homes.
Protestors also formed pyramids and human chains in the sea.