Indian Navy : “The remaining 23 personnel were rescued by the search and rescue ships."
The vessel was on an exercise to recover practice torpedoes fired by fleet ships, when flooding occurred in one of the compartments, the navy said in a statement.
The Indian navy has experienced a spate of accidents at a time when it is trying to modernise and expand its reach to keep up with the rising maritime ambitions of neighbour China.
The torpedo recovery vessel, a TRVA-72, was built by the Shipyard Limited in 1983, according to media reports.
Most of the country’s fleet of more than a dozen submarines is in urgent need of modernisation.
The new government of Prime Minister Narendra Modi has vowed to upgrade India’s military equipment, much of which dates back to the Soviet era, as well as boosting domestic defence manufacturing.