Indonesia's navy has officially ended its efforts to salvage the <em>KRI Nanggala-402</em> submarine, which sank in April off Bali with the loss of all 53 crew, a navy spokesman said on Wednesday. The 44-year-old vessel was discovered broken into three parts at a depth of 840 metres. Authorities had acknowledged the difficulties of retrieving the vessel, despite assistance from countries in the region – including China, Australia and Malaysia. "The salvage effort is over," Indonesian Navy spokesman Julius Widjojono said. Parts of the <em>KRI Nanggala-402 </em>remain on the sea floor. The navy lost contact with the submarine in the early hours of April 21 while it was preparing to conduct a torpedo drill in the Bali Sea. This sparked a desperate international search and rescue effort to locate the submarine before its oxygen supplies ran out. After confirmation that the submarine's crew was lost, Indonesian President Joko Widodo addressed the public, praising the submariners as "the best sons of the nation, the patriots who guard the sovereignty of the country". The tragedy attracted further global attention when a video emerged of the sunken vessel's crew singing a song called <em>Sampai Jumpa</em>, which means "see you later". Submariners have long referred to sunken submarines as being on "eternal patrol". It is thought the phrase was first used during the Second World War, when the status of submarines on combat duty was marked as "on patrol". When the submarines were out of radio contact – and potentially missing – the status remained, leading to the "eternal patrol" status given to sunken submarines.