The missing Indonesian submarine KRI Nanggala 402 with 53 crew, would only have enough oxygen to last until around 03:00 local time on Saturday. That deadline has now passed with no sign of the vessel. There have been no signs of life from the submarine, but family members still held out hope that the massive search effort that has been mounted would find the vessel in time.

“The family is in a good condition and keeps praying," Ratih Wardhani, the sister of 49-year-old crewman Wisnu Subiyantoro told the media. “We are optimistic that the Nanggala can be rescued with all the crew.”

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And with this hope more than two dozen rescue ships from Indonesia and other countries including India are involved in search of the submarine. Yesterday, the search team has identified the area and according to the Indonesian military spokesperson, the rescue vessel has detected an object with "strong magnetic resonance" at a depth of 50 to 100 meters (164 to 328 feet),  After that Indonesia  pressed its warship ‘The Riguel’ equipped with a high-tech sonar, which uses sound waves to locate objects, and the navy is hopeful it will be able to find the KRI Nanggala 402, a German-made submarine which lost contact during an exercise in the Bali Strait early on Wednesday morning.

This is the first incident; Indonesia has lost one of its submarines. Submarine accidents are often disastrous.

Among the worst was the 2000 sinking of the Kursk, the pride of Russia's Northern Fleet. That submarine was on manoeuvres in the Barents Sea when it sank with the loss of all 118 aboard. An inquiry found a torpedo had exploded, detonating all the others. Most of its crew died instantly but some survived for several days before suffocating.

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In 2003, 70 Chinese naval officers and crew were killed, apparently suffocated, in an accident on a Ming-class submarine during exercises in 2003.

Five years later, 20 people were killed by poisonous gas when a fire extinguishing system was accidentally activated on a Russian submarine being tested in the Sea of Japan.

And in 2018, authorities found the wreckage of an Argentine submarine that had gone missing a year earlier with 44 sailors aboard.

The cause of the disappearance of the Indonesian submarine is still uncertain. The navy has said an electrical failure could have left the submarine unable to execute emergency procedures to resurface.

While many countries have offered help, there is no word from China.

The world's largest archipelago nation with more than 17,000 islands has faced growing challenges to its maritime claims in recent years, including numerous incidents involving Chinese vessels near the Natuna islands.

Last year, President Joko Widodo reaffirmed the country's sovereignty during a visit to the islands at the edge of the South China Sea, one of the busiest sea lanes where China is embroiled in territorial disputes with its smaller neighbours.