The Type 209: a German submarine sold around the world
Kolkata, India: The Indonesian submarine which disappeared Wednesday was a German-built model that has served in more than a dozen navies around the world over the past half-century.
The 1,300-tonne KRI Nanggala 402 was a Type 209 diesel-electric attack submarine. Its construction began in 1978 and it was delivered to Indonesia in October 1981.
The KRI Nanggala, which had undergone several upgrades, was participating in naval exercises off the coast of Bali when it requested permission to dive and contact was then lost, authorities said.
There was 53 crew aboard the vessel, which was believed to be in waters about 700 meters (2,300 feet) deep.
The KRI Nanggala was refitted in 1989 in Germany and then in 2012 in South Korea, with part of its structure replaced as well as upgrades made to the propulsion, sonar, and weapons systems.
Indonesia's navy possesses another submarine of the same model, the KRI Cakra, along with three other of different Type 209 models that were built more recently in South Korea and Indonesia, according to Janes, which specializes in military information.
In 1993 Indonesia also acquired 39 used ships from the former East German navy.
Developed in the 1960s to replace WWII-era vessels, the Type 209 was never used by Germany but enjoyed success as an export with 61 sold to over a dozen countries including Greece, India, and Turkey.
Argentina deployed a Type 209 during the Falklands War against Britain.
Egypt received one in April 2020 that was built in the German shipyard where the vessel was developed and which is now owned by industrial giant Thyssenkrupp.
The company says on its website that the Type 209 was inspired by the coastal post-war submarines of the German navy, but enlarged to be able to operate in deeper waters and carry more equipment.
It said the vessel is "the top-selling non-nuclear submarine in the Western World".
The worst submarine accidents
Here are the worst submarine disasters, after Indonesia lost contact with the KRI Nanggala 402 with 53 crew aboard off the coast of Bali at a depth of 700 meters (2,300 feet).
Russia's Kursk, 118 die
In August 2000, Russia's northern fleet nuclear submarine Kursk catches fire and explodes underwater while conducting war games.
Russian authorities controversially initially refuse help from British and Norwegian naval vessels, and all 118 sailors on board the submarine are killed.
Most die instantly but some survive for several days -- with a few keeping heart-breaking diaries written in blood to their loved ones -- before suffocating.
It is the Russian navy's worst-ever disaster.
Chinese navy, all 70 killed
Seventy Chinese naval officers and crew are killed, apparently suffocated, in an accident on a Ming-class submarine conducting exercises east of the Neichangshan islands in May 2003.
The government says only there were "mechanical problems".
Argentina's San Juan, 44 lost
The San Juan, a 34-year-old German-built diesel-electric sub, goes missing with 44 crew aboard in the South Atlantic in mid-November 2017.
It is located at a depth of 900 meters and 400 kilometers (250 miles) from the coast of Patagonia, after a search of more than a year in which several countries take part.
According to the navy, the submarine exploded due to a mechanical breakdown.
Fire on Soviet vessel, 42 die
In April 1989, a fire following a short circuit breaks out on board a Soviet nuclear submarine, the Komsomolets, while it is in international waters 500 kilometers from Norway.
The crew is not able to put out the fire and quickly brings the vessel to the surface. Dozens dive into the glacial waters to escape, only a few taking to lifeboats.
Some drown but most of the 42 dead are taken down in the submarine when it sinks. Twenty-seven people survive.
In March 1979 the Eurydice disappears off the French Mediterranean resort of Saint-Tropez with 57 aboard. The French submarine disintegrated after exploding. Debris is identified the following month at a depth of 900 meters.
Ninety-nine sailors die in May 1968 in an American nuclear submarine, the Scorpion, which disappears in the Atlantic, probably sunk by one of its torpedoes.
Also in 1968 the Soviet K-129 submarine armed with three nuclear missiles disappears with its 98 crew some 2,500 kilometers from Hawaii in the North Pacific.
The United States later finds the wreck 5,000 meters below the surface and organizes its recovery in a covert operation in 1974.
The Minerve, the jewel of France's navy, disappears off Toulon in southern France in January 1968 with 52 sailors on board.
Despite immediate rescue operations, the wreck will only be located half a century later, in July 2019, 45 kilometers from the coast. It has been cut in three.
The Dakar, an Israeli vessel carrying out its maiden voyage with 69 men on board, disappears in January 1968 and is only found off the Greek island of Crete in 1999.
In April 1963 the USS Thresher sinks with 129 people aboard off Cape Cod some 400 kilometers from the northeastern US coast. It is the first American nuclear submarine lost at sea.