The first of six Indian-built DCNS Scorpene-class submarines has started sea trials off the coast of Mumbai, the Indian Ministry of Defense reports.

The diesel-electric vessel was built at Mazagon Dock Shipbuilders Ltd. under a technology transfer deal with DCNS of France and is named the Kalvari.

The vessel is scheduled for commissioning at the end of this year.

The sea trial occurred Sunday and was the first. Additional trials are to take place in months to come. Among systems being tested are the vessel's propulsion system, auxiliary equipment and systems, navigation aids, communication equipment and steering gear.

"This important milestone was achieved by MDL after overcoming a number of challenges faced since launching of the submarine last year in October," the Ministry of Defense said. "During the next few months, the submarine will undergo a barrage of sea trials, including surface trials, diving trials, weapon trials ... which will test the submarine to the extremes of its intended operating envelop."

Scorpene-class diesel-electric submarines displace 1,725 tons. They are 202 feet long, have a maximum submerged speed of 20 knots, and a normal endurance of 50 days.