It happened 20 years ago today and has spawned films, books and numerous articles ? but the reason for the sinking of Soviet submarine K-219 600 miles from Bermuda is still not known.

The Yankee-class ballistic missile vessel, laden with nuclear warheads and 200 tons of radioactive plutonium, plunged 18,000 feet beneath the waves on October 6, 1986, after an explosion on board three days earlier.

The Soviet Union claimed at the time that the explosion and a subsequent fire ? which killed four crew members ? was due to a collision with a US submarine.

But the US Navy categorically denied that and the submarine?s captain, Igor Britanov, later told an interviewer: ?There was no collision.?

Two decades on, details are still sketchy about exactly what occurred onboard the 10,000 ton, 425ft long submarine, which had 113 men onboard.

A book published in 1997, Hostile Waters, hinted at a collision between the American submarine USS Augusta and K-219 over her missile compartment as the cause of the explosion.

Author Peter Huchthausen, a former US Navy officer and ex-naval attach?, also detailed the bravery of the Russian crew, from Capt. Britanov, who he said refused to comply with orders to keep his men onboard the ship before it sank, to Sergei Preminin, the 21-year-old engineer seaman who lost his life after manually shutting down the submarine?s reactors and averting a potentially huge disaster.

Three others died on board and many more of the crew suffered permanent injury.

Preminin received a posthumous award in his home country for his bravery and was named a Hero of the Russian Federation in 1997.

Some believe his heroism should be marked on the Island, arguing that his actions stopped deadly reactor fuel spewing into the sea and air in the Gulf Stream, which could have caused havoc in Bermuda and far beyond.

The K-219 accident was dubbed a ?maritime Chernobyl? by environmental group Greenpeace. But fears that the sub could leak radioactive waste into the ocean and potentially cause problems for Bermuda?s marine life were dismissed by scientists.

Dr. Tony Michaels, from Bermuda Biological Station for Research, told The Royal Gazette in 1994 that the chance of any harmful effect was ?about zero?.

?There is no way that something in the water 5,000 metres deep, 500 miles east of here, could affect the water around the Island,? he said.

Premier John Swan, back in 1986, said the Island had been assured by British authorities that there was ?no danger? of a radioactive leak.

A year-long criminal investigation followed the sinking of the K-219.

Capt. Britanov, along with two others, was discharged for failing to perform his duties properly and accused of treason, sabotage and negligence.

The charges were later dropped as the Soviet Union dissolved and the seaman later won damages from Warner Brothers after the studio made a film about the incident in which he claimed he was wrongly portrayed as incompetent.

In 1998, Capt. Britanov was asked by interviewer Lt. Cdr. Wayne Grasdock what lesson could be learnt from the incident. ?Take care of your people and they will take care of you,? he replied.

In Seaman Preminin?s hometown in Russia, there is a monument which pays tribute to his actions. The inscription reads: ?To Russian Seaman Sergei Preminin, who prevented the world from a nuclear catastrophe.?

Do you think the bravery of Seaman Preminin should be commemorated in Bermuda? Write to the Editor at the usual address or e-mail news@royalgazette.bm.