There were 53 sailors on board the vessel when it sank.
“We all feel so bereaved about this incident,” Marshal Hadi Tjahjanto told the press Saturday.
“The elements of the Navy have found oil spill and debris, which are authentic evidence of the sinking phase of the KRI Nanggala [402 submarine],” he said at a press conference in Bali Saturday.
The multi-nation search effort for the submarine will continue.
The chief of staff of the Indonesian Navy, Admiral Yudo Margono, said the debris recovered from the search and rescue effort belonged to the missing submarine.
“Items have been found in the vicinity of the submarine’s last seen location during the dive, which are believed to be parts or components that are embedded in the submarine and this will not be lifted [to the surface] if there is no external pressure or cracks in the torpedo launcher,” Yudo said.
“And these items are not owned by the public, and around a 10-mile radius, there are no other ships that pass,” Yudo continued. “It is believed that these properties belong to KRI Nanggala.”
Despite declaring the submarine sunk, officials have avoided declaring the fate of the crew, saying that they “still may be safe.” Yudo even floated the remote possibility that if the submarine did not experience a complete blackout, oxygen can last an additional two days.
However, Yudo believes the submarine is now at a depth of 850 meters (nearly 2,790 feet), which is beyond the KRI Nanggala’s maximum operating depth of 250-500 meters.
The press conference showed various items purportedly found from the submarine, including torpedo tube straightener, pipe cooling wrap, lubricant for the submarine periscope, sponges and submarine solar.
Yudo ruled out the possibility that the submarine exploded underwater as the condition of the debris recovered suggested the vessel cracked.
“Cracks, so it is not an explosion. If there is an explosion, it must have destroyed everything,” Yudo said, adding that if there was an explosion, the acoustics would have been picked up on sonar.
The 44-year-old German-made submarine was part of the Indonesian Navy’s 2nd Fleet. It was taking part in a torpedo training exercise early Wednesday morning in the waters north of Bali when it suddenly lost contact with the other vessels involved. Officials previously estimated that the vessel only had a 72-hour supply of oxygen onboard. The local press reported that the vessel might have been overloaded past the usual operating capacity of a submarine in its class, which is 40 sailors.
A multinational rescue effort including the US, Australia, Singapore and Malaysia have joined Indonesia in the search and rescue effort with the Pentagon deploying a U.S. Navy P-8 Poseidon aerial reconnaissance plane from the Philippines.