There is little hope of finding survivors from a missing Indonesian submarine, the country’s navy said Saturday, after officials declared the vessel had sunk.

“We have now moved from the ‘sub miss’ phase to ‘sub sunk,'” Indonesian navy Chief of Staff Adm. Yudo Margono told a news conference, where he showed debris including a torpedo straightener and Islamic prayer rugs from the submarine.

“We are still carrying out the search … the depth of the sea we have detected is at 850 meters (2,790 feet), which is very tricky and presents many difficulties,” he said.

Earlier this week the navy said that it thought the vessel had sunk to a depth of 600-700 meters (2,000-2,300 feet), much deeper than its collapse depth of 200 meters (655 feet), at which point the water pressure would be greater than the hull could withstand.

Oxygen supplies for the 53 crew members on board the German-built “KRI Nanggala 402” had also likely now run out, Margono added.