Rescue teams from several countries are battling against time to find a missing Indonesian navy submarine that lost contact with land two days ago with 53 crew on board.
The country's navy has been searching for the vessel ever since it went missing during a training exercise in waters north of the island of Bali.
The 43-year-old sub was conducting a torpedo drill on Wednesday but failed to relay the results as expected and has been silent ever since.
Yudo Margono, the navy chief of staff, has warned there is only enough oxygen for the sailors to last until 3am on Saturday local time - 8pm on Friday GMT.
Search helicopters and more navy ships left Bali and a naval base in Java at first light and headed to the area where contact was lost.
Australia, India, Malaysia, Singapore and the US have sent specialised ships or aircraft in response to
Indonesian requests for assistance.
The US defence department has sent "airborne assets" and Australia has despatched two navy ships including a frigate with special sonar capabilities.
Indonesia's navy said it was investigating whether the KRI Nanggala-402 submarine perhaps lost power during a dive and could not carry out emergency procedures as it descended to a depth of 600-700m (1,970ft-2,300ft), well beyond its survivable limits.
However, on Thursday an object with "high magnetic force" had been spotted "floating" at a depth of 50-100m (164ft-328ft), and an aerial search had earlier spotted an oil spill near the submarine's last location.
Berda Asmara, the wife of crew member Guntur Ari Prasetyo, 39, said when she last spoke to her husband before he set sail he "asked me to pray for him".
She added: "I hope that they will be found alive."
Connie Rahakundini Bakrie, an Indonesian defence expert, said there was hope they could survive but warned: "If the submarine is in a 700-metre sea trough, it will be difficult for them to survive because underwater pressure will cause cracks and ruptures of the steel hull."
The Bali Sea can reach depths of more than 1,500m (4,921ft)
Indonesian President Joko Widodo said the priority was "the safety of the 53 crew members".
One of them is the commander of the Indonesian submarine fleet, Harry Setiawan.
The submarine joined the Indonesian fleet in 1981, according to the defence ministry, and underwent a refit in South Korea completed in 2012.
It was said to be in good condition.