"We received underwater pictures that are confirmed as parts of the submarine, including its rear vertical rudder, anchors, outer pressure body, embossed dive rudder and other ship parts," military chief Hadi Tjahjanto said on Sunday, four days after the vessel went missing off the resort island of Bali.
"With this authentic evidence, we can declare that KRI Nanggala 402 has sunk and all the crew members are dead," Tjahjanto added.
An underwater robot equipped with cameras documented the lost submarine lying in at least three pieces on the ocean floor at a depth of 2,750 feet, said Adm. Yudo Margono, the navy’s chief of staff.
That’s much deeper than the submarine’s collapse depth of 655 feet, at which point water pressure would be greater than the hull could withstand, according to earlier navy statements.
The cause of the submarine’s sinking remains uncertain.
The navy previously said an electrical failure could have left the submarine unable to execute emergency procedures to resurface.
Margono said emergency survival suits that are normally kept in boxes were found floating underwater, apparently indicating the crew may have tried to put them on during the emergency.
The wreckage is located 1,500 yards to the south of the site where the submarine last dove off Bali’s northern coast, Margono said.
The underwater robot deployed by Singaporean vessel MV Swift Rescue provided the images of the wreckage, while the Indonesian vessel KRI Rigel had scanned the area where the submarine was believed to have sunk using multibeam sonar and a magnetometer, Tjahjanto said.
The navy plans to eventually lift the wreckage and recover the dead, although the depth of the water poses a significant challenge, Margono said.
Indonesia’s President Joko Widodo delivered his condolences in a televised address Sunday.
"All Indonesians convey deep sorrow for this tragedy, especially to all of the families of the submarine’s crew. They are the best sons of the nation, patriots guarding the sovereignty of the country," Widodo said.
The German-built diesel-powered KRI Nanggala 402 had been in service in Indonesia since 1981 and was carrying 49 crew members and three gunners as well as its commander, the Indonesian Defense Ministry said.
The Associated Press contributed to this report.