The German-built KRI Nanggala-402 was discovered at a depth of nearly 840 meters (2,756 ft) on Sunday (April 25), broken into at least three parts, four days after it lost contact while preparing to conduct a torpedo drill.
Retrieval operations are still ongoing at sea with help from international search teams, as authorities struggle to figure out how to lift the wreckage. Experts warn that it will be a daunting task to lift the submarine to the surface, requiring specialised salvage equipment.
Indonesia operates five submarines - two German-built Type 209s including Nanggala and three newer South Korean vessels. It has been seeking to modernise its defence capabilities but some of its equipment is old and there have been fatal accidents in recent years.