The chief of the Indonesian Navy, Adm. Yudo Margono explained during a press conference that several debris belonging to the submarine were found during the search process, namely a torpedo tube straightener, a cooling pipe wrapper, and an orange bottle of submarine periscope lubricant. Evidence found by the rescue effort suggests that it is sunk in over 800 meters of water.
“With the authentic evidence, at this point we change the status of KI Nanggala from SUBMISS to SUBSUNK”
Chief of the Indonesian Armed Forces Air Chief Marshal Hadi Tjahjanto
UPDATE:
— JATOSINT (@Jatosint) April 24, 2021
-Debris, grease/lubricant, and oil which is believed to come from KRI Nanggala has been found, thus SUBSUNK has been officially declared
-It is predicted that the sub is sunk at 700-800 meters depth
-In a best-case scenario, oxygen can last up to 120-hours pic.twitter.com/Gfmzzg0zLJ
For the record, Indonesian Navy Type-209 /1300 class Submarine KRI Nanggala (402) was reported missing on 21 April 2021 in waters north of Bali after missing a radio check-in. There were 53 sailors aboard.
Both Type 209/1300 (Cakra-class) submarines of the Indonesian Navy, KRI Cakra and KRI Nanggala were built by Germany’s Howaldtswerke-Deutsche Werft (HDW, TKMS) in 1981. They have a length of 59.5 meters, an underwater displacement of 1,390 tons, a test depth of 240 meters and an endurance of 50 days.
Here is a list of tragic submarine accidents which occured in the past twenty years. As Covert Shores fittingly puts it, “The fate of a missing submarine plays on the minds of those in any way connected to submarine operations.”

Update
UPDATE
— JATOSINT (@Jatosint) April 25, 2021
-Nanggala's hull has been found crushed/damaged at 09:04 AM UTC +9 at depth of 838 meters. All hands lost.
-Submarine Escape Suite can be seen (🟧object), indicating an escape attempt by the crew
-Navy hopes that the hull can be salvage & raised for investigation pic.twitter.com/1k6aIG9kUv