The Indonesian Navy has declared its missing submarine has sunk and cracked open after finding items from the vessel over the past two days.
Indonesian Navy chief Yudo Margono said no bodies have been found so far.
Military chief Hadi Tjahjanto said the presence of an oil slick, as well as debris near the site of the submarine's last dive on Wednesday off the island of Bali, were clear proof the KRI Nanggala 402 sank.
Mr Margono told a press conference in Bali: "If it's an explosion, it will be in pieces.
"The cracks happened gradually in some parts when it went down from 300 metres to 400 metres to 500 metres... if there was an explosion, it would be heard by the sonar."
The navy previously said it believes the submarine sank to a depth of 600-700 metres (2,000-2,300 feet), much deeper than its collapse depth of 200 metres (655 feet), the point at which water pressure would be greater than the hull could withstand.
The cause of the disappearance is still uncertain.
The Indonesian Navy has said an electrical failure could have left the submarine unable to execute emergency procedures to resurface.
The submarine was expected to run out of oxygen by roughly 03:00 local time on Saturday 24 April.
Mr Margono added that in the past two days, searchers found parts of a torpedo straightener, a grease bottle believed to be used to oil the periscope, debris from prayer rugs and a broken piece from a coolant pipe that was refitted on the submarine in South Korea in 2012.
"With the authentic evidence we found believed to be from the submarine, we have now moved from the 'sub miss' phase to 'sub sunk'."
He added that rescue teams from Indonesia and other countries will evaluate the findings.
Indonesian President Joko Widodo had ordered all-out efforts to locate the submarine and asked Indonesians to pray for the crew's safe return.
An American reconnaissance plane, a P8 Poseidon, landed early Saturday and had been set to join the search, along with 20 Indonesian ships, a sonar-equipped Australian warship and four Indonesian aircraft.
Singaporean rescue ships were also expected on Saturday, while Malaysian rescue vessels were due to arrive on Sunday, bolstering the underwater hunt, officials said earlier.
The German-built diesel-powered KRI Nanggala 402 has been in service in Indonesia since 1981 and was carrying 49 crew members and three gunners as well as its commander, the Indonesian defence ministry said.
Indonesia, the world's largest archipelago nation with more than 17,000 islands, has faced growing challenges to its maritime claims in recent years, including numerous incidents involving Chinese vessels near the Natuna Islands.
Picture: Indonesian Navy.