On August 12, 2000, the Russian Oscar II class submarine, Kursk sank in the Barents Sea. The generally accepted theory is that a leak of hydrogen peroxide in the forward torpedo room led to the detonation of a torpedo warhead, which in turn triggered the explosion of half a dozen other warheads about two minutes later. This second explosion was equivalent to about 3-7 tons of TNT and was large enough to register on seismographs across Northern Europe. Despite a rescue attempt by British and Norwegian teams, all 118 sailors and officers aboard Kursk were lost. A Dutch team later recovered the wreckage and all of the bodies, which were laid to rest in Russia.

More information on the explosion:
The tragedy began on the morning of August 12, 2000. As part of a naval exercise, Kursk was to fire two dummy torpedoes at a Kirov-class battlecruiser, Peter the Great, the flagship of the Northern Fleet. At 11:28 local time (07:28 UTC), high test peroxide (HTP), a form of highly concentrated hydrogen peroxide used as propellant for the torpedo, seeped through rust in the torpedo casing. The HTP reacted with copper and brass in the tube from which the torpedo was to be fired, causing a chain reaction leading to a chemical explosion. A similar incident was responsible for the loss of HMS Sidon in 1959. The watertight door separating the torpedo room from the rest of the submarine was left open prior to firing. This was apparently common practice, due to the amount of compressed air released into the torpedo room when a torpedo was launched. The open door allowed the blast to rip back through the first two of nine compartments on the huge submarine, probably killing the seven men in the first compartment, and at least injuring or disorienting the thirty-six men in the second compartment. After the first explosion, due to the fact the air conditioning duct was quite light, the blast wave traveled to more compartments, including the command post, filling them with smoke and flames. After the explosion, the captain was believed to be trying to order an 'emergency blow' which causes the sub to rapidly rise to the surface, but he was quickly overcome with smoke. An emergency buoy, designed to release from a submarine automatically when emergency conditions such as rapidly changing pressure or fire are detected and intended to help rescuers locate the stricken vessel, also failed to deploy. The previous summer, in a Mediterranean mission, fears of the buoy accidentally deploying, and thereby revealing the sub's position to the U.S. fleet, had led to the buoy being disabled. Two minutes and fifteen seconds after the initial eruption, a much larger explosion ripped through the submarine. Seismic data from stations across Northern Europe show that the explosion occurred at the same depth as the sea bed, suggesting that the submarine had collided with the sea floor which, combined with rising temperatures due to the initial explosion, had caused other torpedoes to explode. The second explosion was equivalent to 3–7 tons of TNT, or about a half-dozen torpedo warheads and measured 3.5 on the Richter scale. After the second explosion, the nuclear reactors were shut down to prevent a nuclear disaster, although the blast was almost enough to destroy the reactors. The second explosion ripped a two-metre-square hole in the hull of the craft, which was designed to withstand depths of 1000 meters. The explosion also ripped open the third and fourth compartments. Water poured into these compartments at 90,000 litres per second – killing all those in the compartments, including five officers from 7th SSGN Division Headquarters. The fifth compartment contained the ship's nuclear reactors, encased in a further five inches of steel. The bulkheads of the fifth compartment withstood the explosion, causing the nuclear control rods to stay in place and prevent nuclear disaster. Twenty-three men working in the sixth through to ninth compartments survived the two blasts. They gathered in the ninth compartment, which contained the secondary escape tunnel (the primary tunnel was in the destroyed second compartment). Captain-lieutenant Dmitri Kolesnikov (one of three officers of that rank surviving) appears to have taken charge, writing down the names of those who were in the ninth compartment. The air pressure in the compartment following the second explosion was still normal surface pressure. Thus it would be possible from a physiological point of view to use the escape hatch to leave the submarine one man at a time, swimming up through 100 metres of Arctic water in a survival suit, to await help floating at the surface. It is not known if the escape hatch was workable from the inside – opinions still differ about how badly the hatch was damaged. However it is likely that the men rejected using the perilous escape hatch even if it were operable. They may have preferred instead to take their chances waiting for a rescue vessel to clamp itself onto the escape hatch. It is not known with certainty how long the remaining men survived in the compartment. As the nuclear reactors had automatically shut down, emergency power soon ran out, plunging the crew into complete blackness and falling temperatures. Kolesnikov wrote two further messages, much less tidily than before. In the last, he wrote:

"It's dark here to write, but I'll try by feel. It seems like there are no chances, 10-20%. Let's hope that at least someone will read this. Here's the list of personnel from the other sections, who are now in the ninth and will attempt to get out. Regards to everybody, no need to be desperate. Kolesnikov."
There has been much debate over how long the sailors might have survived. Some, particularly on the Russian side, say that they would have died very quickly; water is known to leak into a stationary Oscar-II craft through the propeller shafts and at 100m depth it would have been impossible to plug these. Others point out that the many superoxide chemical cartridges, used to absorb carbon dioxide and chemically release oxygen to enable survival, were found used when the craft was recovered, suggesting that they had survived for several days. Ironically, the cartridges appear to have been the cause of death; a sailor appears to have accidentally brought a cartridge in contact with the sea water, causing a chemical reaction and a flash fire. The official investigation into the disaster showed that some men appeared to have survived the fire by plunging under the water (the fire marks on the walls indicate the water was at waist level in the lower area at this time). However the fire rapidly used up the remaining oxygen in the air, causing death by asphyxiation. According to Raising Kursk broadcast by the Science Channel: "In June of 2002, the Russian Navy recovered Kursk's bow section. Shortly afterwards, the Russian government investigation into the accident officially concluded that a faulty torpedo sank Kursk in the Summer of 2000."

On August 12, 2000, the Russian Oscar II class submarine, Kursk sank in the Barents Sea. The generally accepted theory is that a leak of hydrogen peroxide in the forward torpedo room led to the detonation of a torpedo warhead, which in turn triggered the explosion of half a dozen other warheads about two minutes later. This second explosion was equivalent to about 3-7 tons of TNT and was large enough to register on seismographs across Northern Europe. Despite a rescue attempt by British and Norwegian teams, all 118 sailors and officers aboard Kursk were lost. A Dutch team later recovered the wreckage and all of the bodies, which were laid to rest in Russia.

More information on the explosion:
The tragedy began on the morning of August 12, 2000. As part of a naval exercise, Kursk was to fire two dummy torpedoes at a Kirov-class battlecruiser, Peter the Great, the flagship of the Northern Fleet. At 11:28 local time (07:28 UTC), high test peroxide (HTP), a form of highly concentrated hydrogen peroxide used as propellant for the torpedo, seeped through rust in the torpedo casing. The HTP reacted with copper and brass in the tube from which the torpedo was to be fired, causing a chain reaction leading to a chemical explosion. A similar incident was responsible for the loss of HMS Sidon in 1959. The watertight door separating the torpedo room from the rest of the submarine was left open prior to firing. This was apparently common practice, due to the amount of compressed air released into the torpedo room when a torpedo was launched. The open door allowed the blast to rip back through the first two of nine compartments on the huge submarine, probably killing the seven men in the first compartment, and at least injuring or disorienting the thirty-six men in the second compartment. After the first explosion, due to the fact the air conditioning duct was quite light, the blast wave traveled to more compartments, including the command post, filling them with smoke and flames. After the explosion, the captain was believed to be trying to order an 'emergency blow' which causes the sub to rapidly rise to the surface, but he was quickly overcome with smoke. An emergency buoy, designed to release from a submarine automatically when emergency conditions such as rapidly changing pressure or fire are detected and intended to help rescuers locate the stricken vessel, also failed to deploy. The previous summer, in a Mediterranean mission, fears of the buoy accidentally deploying, and thereby revealing the sub's position to the U.S. fleet, had led to the buoy being disabled. Two minutes and fifteen seconds after the initial eruption, a much larger explosion ripped through the submarine. Seismic data from stations across Northern Europe show that the explosion occurred at the same depth as the sea bed, suggesting that the submarine had collided with the sea floor which, combined with rising temperatures due to the initial explosion, had caused other torpedoes to explode. The second explosion was equivalent to 3–7 tons of TNT, or about a half-dozen torpedo warheads and measured 3.5 on the Richter scale. After the second explosion, the nuclear reactors were shut down to prevent a nuclear disaster, although the blast was almost enough to destroy the reactors. The second explosion ripped a two-metre-square hole in the hull of the craft, which was designed to withstand depths of 1000 meters. The explosion also ripped open the third and fourth compartments. Water poured into these compartments at 90,000 litres per second – killing all those in the compartments, including five officers from 7th SSGN Division Headquarters. The fifth compartment contained the ship's nuclear reactors, encased in a further five inches of steel. The bulkheads of the fifth compartment withstood the explosion, causing the nuclear control rods to stay in place and prevent nuclear disaster. Twenty-three men working in the sixth through to ninth compartments survived the two blasts. They gathered in the ninth compartment, which contained the secondary escape tunnel (the primary tunnel was in the destroyed second compartment). Captain-lieutenant Dmitri Kolesnikov (one of three officers of that rank surviving) appears to have taken charge, writing down the names of those who were in the ninth compartment. The air pressure in the compartment following the second explosion was still normal surface pressure. Thus it would be possible from a physiological point of view to use the escape hatch to leave the submarine one man at a time, swimming up through 100 metres of Arctic water in a survival suit, to await help floating at the surface. It is not known if the escape hatch was workable from the inside – opinions still differ about how badly the hatch was damaged. However it is likely that the men rejected using the perilous escape hatch even if it were operable. They may have preferred instead to take their chances waiting for a rescue vessel to clamp itself onto the escape hatch. It is not known with certainty how long the remaining men survived in the compartment. As the nuclear reactors had automatically shut down, emergency power soon ran out, plunging the crew into complete blackness and falling temperatures. Kolesnikov wrote two further messages, much less tidily than before. In the last, he wrote:

"It's dark here to write, but I'll try by feel. It seems like there are no chances, 10-20%. Let's hope that at least someone will read this. Here's the list of personnel from the other sections, who are now in the ninth and will attempt to get out. Regards to everybody, no need to be desperate. Kolesnikov."
There has been much debate over how long the sailors might have survived. Some, particularly on the Russian side, say that they would have died very quickly; water is known to leak into a stationary Oscar-II craft through the propeller shafts and at 100m depth it would have been impossible to plug these. Others point out that the many superoxide chemical cartridges, used to absorb carbon dioxide and chemically release oxygen to enable survival, were found used when the craft was recovered, suggesting that they had survived for several days. Ironically, the cartridges appear to have been the cause of death; a sailor appears to have accidentally brought a cartridge in contact with the sea water, causing a chemical reaction and a flash fire. The official investigation into the disaster showed that some men appeared to have survived the fire by plunging under the water (the fire marks on the walls indicate the water was at waist level in the lower area at this time). However the fire rapidly used up the remaining oxygen in the air, causing death by asphyxiation. According to Raising Kursk broadcast by the Science Channel: "In June of 2002, the Russian Navy recovered Kursk's bow section. Shortly afterwards, the Russian government investigation into the accident officially concluded that a faulty torpedo sank Kursk in the Summer of 2000."