The concern is growing in Indonesia for the lives of the 53 crew members who went missing, along with the KRI Nanggala 402 submarine. They were onboard during training, submerged in the waters near the island of Bali on April 21.

According to Indonesian military spokesman Maj. Gen. Achmad Riad, search-and-rescue teams are straining to the utmost in their race against the clock, given that the sailors have less than 20 hours of oxygen to preserve their lives. Gen. Achmad Riad, according to Fox News, April 23. 

“We will maximize the effort today, until the time limit tomorrow 3 a.m.,” Riad emphasized, noting that would be the maximum time for the duration of oxygen supplies for the crew.

On the other hand, a worrisome oil slick that appeared on the sea’s surface became the focus of the search, on which the search was concentrated.  

Today, 24 vessels, including the Navy and other ships and a patrol plane, were expected to participate in the search. Rescuers conducted similar massive searches over the past two days.

Australia offered two vessels to expand the search area. One of them is equipped with sonar equipment. It would also be joined later by a helicopter.

Additionally, Singapore and Malaysia will send other vessels to increase the scanning power in the coming days.

However, some indications point to a gloomy outlook on the fate of the helpless crew. 

While the oil slick that serves as the linchpin for the search could be indicative of maneuvers by the crew to lighten the weight and increase their chances of getting afloat, a team of South Korean experts who refitted the submarine between 2009 and 2012 believes that the vessel is well past its collapse depth.

For the South Korean company, the KRI Nanggala 402 could safely submerge to 200 meters (655 feet). Still, they estimate that it could already be below 600 meters (2,000-2,300 feet), making it possible to predict that it has exceeded the water pressure it could withstand.

For its part, the United States also announced that it would send aircraft, according to statements by Pentagon press secretary John Kirby.

 “We are deeply saddened by the news of Indonesia’s lost submarine, and our thoughts are with the Indonesian sailors and their families,” Kirby said. 

According to Indonesia’s Department of Defense, the submarine had been in use for 40 years.

Similar tragedies have been repeated on several occasions in various countries—one of the most recent ones registered in 2017, aboard the Argentine-flagged submarine ARA San Juan. 

In it, 44 crew members perished as victims of the ARA San Juan submarine shipwreck, in which 44 crew members were traveling on Nov. 15, 2017.

Not far from the place where the faults were reported, about 500 kilometers away from the city of Comodoro Rivadavia, in the province of Chubut, Argentina, the Norwegian-flagged vessel Seabed Constructor found the remains of the submarine using the ROV remote observation vehicle and at a depth of 800 meters.