A submarine belonging to Indonesia's Navy has gone missing off the coast of Bali, with 53 people on board. The KRI Nanggala-402 sub was conducting a torpedo drill north of Bali early Wednesday when it vanished about 60 miles from shore, per Reuters and the BBC. The country has requested the help of Australia and Singapore while warships search the area, which is "quite deep," First Admiral Julius Widjojono says, per CBS News. The sub reportedly lost contact after it was granted clearance to dive to greater depths, per the BBC. The Navy believes it may have sank into a 2,300-foot-deep trench, per the AP.
Widjojono said the last contact came around 3am local time. The sub was said to be rehearsing for a missile-firing exercise scheduled for Thursday, which military chief Hadi Tjahjanto and other military leaders were expected to attend, per the AP. The sub—one of only five kept by Indonesia's Navy—was made in Germany in 1978 but underwent a two-year retrofit in South Korea before returning to the water in 2012, per Reuters. The outlet notes Indonesia has a habit of using old military equipment. Two military transport planes crashed in the country in 2015 and 2016, killing more than 100 people combined. (Read more Indonesia stories.)