The death toll from the capsizing stood at 21 late Sunday, and an investigation into the cause was being organized, the lieutenant governor of Andaman and Nicobar Islands said.
The boat was making its way from Ross Island to North Bay when it overturned. It was unclear whether any of the passengers or crew were missing.
The tourists were mainly from India, including a group of 30 from Tamil Nadu.
Officials told NDTV 13 people had been rescued and taken to a hospital in Port Blair.
Press Trust of India said sources reported the boat had an official capacity of 25 people and was overloaded during the trip to a resort.