Indonesia’s navy has officially ended its efforts to salvage the KRI Nanggala-402 submarine, which sank in April in the waters off Bali island claiming all 53 lives on board, a navy spokesman reported on Wednesday.

Discovered in 3 parts at a depth of 840 metres (2756 ft), authorities had acknowledged the difficulties of retrieving the vessel.

On April 25,  army and navy officials said a missing Indonesian submarine was found, broken into at least three parts, at the bottom of the Bali Sea, as the president sent condolences to relatives of the 53 crew.

Rescuers also found new objects, including a life vest, that they believe belong to those aboard the 44-year old KRI Nanggala-402, which lost contact as it prepared to conduct a torpedo drill.

Navy chief of staff Yudo Margono said the crew were not to blame for the accident and that the submarine did not experience a blackout, blaming “forces of nature”.

“The KRI Nanggala is divided into three parts, the hull of the ship, the stern of the ship, and the main parts are all separated, with the main part found cracked,” he said. “There are scattered parts of the submarine and its interior in the water.”