Time - and oxygen - is running out as the search for a missing Indonesian submarine continues

A member of Indonesian military looks on the pictures of Indonesian Navy submarine KRI Nanggala crew members that went missing while participating in a training exercise on Wednesday
Associated Press
Rescuers searching for the Indonesian submarine say they must stay "optimistic."
Oxygen levels were due to run out on the missing sub.
The Indonesian submarine disappeared during a training exercise this week.
See more stories on Insider's business page.
Rescuers searching for the Indonesian submar