- 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 metres and 400 kilometres (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 kilometres 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.

- Other accidents -

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 metres.

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 kilometres from Hawaii in the North Pacific.

The United States later finds the wreck 5,000 metres below the surface and organises 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 kilometres 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 kilometres from the northeastern US coast. It is the first American nuclear submarine lost at sea.