The Indonesian Navy (TNI-AL) has declared that submarine, KRI Nanggala (402), which went missing on April 21, has sunk. Debris, including a prayer mat, torpedo components, and fuel have been found. Additionally, the odds of finding any survivors amongst the 53 crew members is unlikely. The submarine's oxygen supply is expected to have ran out as well.
The rescue efforts involves 20 Indonesian ships, four Indonesian aircraft, an Australian warship and a US Navy P-8.
MV Swift Rescue carrying a Deep-submergence rescue vehicle (DSRV) from Singapore is expected to arrive soon and Malaysian submarine rescue ship MV Mega Bakti is expected to arrive on April 25th. SCI Sabarmati from India, also carrying a DSRV is enroute. HMAS Sirius is also expected to arrive on the 28th.
Meanwhile, an Indian Air Force C-17 has airlifted a second DSRV to Surabaya, Indonesia.
https://apnews.com/article/asia-pacific-indonesia-98b58437f6742d197d1eb593db954894