Indonesia has about 72 hours left to rescue 53 crew members of a missing navy submarine before they run out of oxygen, the navy said.
The KRI Nanggala-402 vessel is thought to have disappeared about 60 miles (100km) off the coast of Bali early on Wednesday morning.
Six warships, a helicopter and 400 people are involved in the search.
Singapore and Malaysia have dispatched ships, and the US, Australia, France, and Germany have offered assistance.
The German-built submarine had been conducting a drill but failed to report back and contact was lost, the navy said.
“We know the area but it’s quite deep,” First Admiral Julius Widjojono told the AFP news agency.
Some reports said contact was lost with the submarine after it was given clearance to dive into deeper waters.
Meanwhile, an oil spill found near where the submarine dived could point to fuel tank damage, or could also be a signal from the crew, the navy said.