Nanggala had 53 people on board, including 49 crew members, 1 commander, and 3 weapons specialists.

[39] The highest-ranking naval officer in the submarine was Colonel Harry Setyawan, the commander of the submarine unit of the 2nd Fleet Command.

KRI Nanggala (402), also known as Nanggala II, was one of two Cakra-class Type 209/1300 diesel-electric attack submarines of the Indonesian Navy. On 21 April 2021, the submarine sank in the Bali Sea during a torpedo drill, killing all 53 personnel on board

Name: KRI Nanggala

Namesake: Divine spear of Prabhu Baladewa

Ordered: 2 April 1977

Builder: Howaldtswerke-Deutsche Werft

Laid down: 14 March 1978

Launched: 10 September 1980

Completed: 6 July 1981

Commissioned: 21 October 1981

Out of service: 21 April 2021

Identification no: Pennant number 402

Fate: Sank during torpedo drill, 21 April 2021

Malaysia, Australia, Singapore, and India

The Republic of Singapore Navy and Royal Malaysian Navy deployed their submarine rescue vessels, MV Swift Rescue and MV Mega Bakti respectively, to the scene

On 22 April, at approximately 14:15 WIB (07:15 UTC),[55] the Indian Navy announced that their deep-submergence rescue vehicle (DSRV) had departed naval facilities at Visakhapatnam, Andhra Pradesh, end route to the search area.[56] U.S. Department of Defense press secretary John Kirby stated that the department was sending airborne assets to assist in the search.[38]

The U.S. sent a P-8 Poseidon maritime patrol aircraft, which landed Saturday. On 23 April, Commander Australian Fleet Rear Admiral Mark Hammond announced that HMAS Ballarat and HMAS Sirius would join the search operation. Other nations, including Germany, France, Russia, Turkey, and Thailand, offered assistance

On 27 April 2021 at a press conference at the naval headquarters at Cilangkap, East Jakarta, he explained the experience of total black-out while submerged. In 10 seconds, the submarine sank 90m, tail first at 45 degree, and the crew were ordered to moved forward to balance the ship. But since the submarine was at a steep angle, he had to crawl on his knees, said Iwan as he paused, emotionally-overcome by the incident.

Further Hasanuddin stated that oxygenation gel, used in the Nanggala to release additional oxygen gas, was not carried onboard the submarine when it sailed out to sea for the execise.

On April 24, the Navy announced that Nanggala had been confirmed sunk. Earlier, debris suspected to have originated from Nanggala was found, including fragments of torpedo tube rectifiers, cooling pipe coverings, periscope lubricants and prayer mats. [26] Currently, Nanggala is said to be at a depth of 850 meters, well below the maximum operating depth of 500 meters.