The sudden evacuation mission was initiated at the request of the A&N disaster management, which speculates that a "cyclonic storm" might struck Havelock, an island about 36 km from capital Port Blair.
"There is a deep depression (in the sea) about 310 kms from Port Blair. That is why the Navy was contacted as we don't want to take any chances," an official from Directorate of Disaster Management, A&N administration, told IANS.
The official said that because of heavy rains and winds, the difficulty tourists are facing is to reach the jetty to board the ships.
"We can't say as of now that the depression will turn into a cyclone," the official said.
They expect the evacuation to be completed by the evening, he said.
Navy spokesperson Captain D.K. Sharma said the ships were in the area and that there was a bad sea state.
He said the ships departed from Port Blair around 0315 hours onwards.
The official said the Indian Navy has sent four ships -- INS Bitra, Bangaram, Kumbhir and LCU 38 -- for the evacuation.
Sharma said all the ships will go alongside and ferry tourists to Port Blair. Their highest consideration is safety of the tourists.