[3] During her five years of service, Kursk completed only one mission, a six-month deployment to the Mediterranean Sea during the summer of 1999 to monitor the United States Sixth Fleet responding to the Kosovo crisis.

[3] Two days later, on the morning of 12 August, Kursk prepared to fire dummy torpedoes at the Kirov-class battlecruiser Pyotr Velikiy.

[14] The Russian Navy's final report on the disaster concluded the explosion was due to the failure of one of Kursk's hydrogen peroxide-fueled Type 65 torpedoes.

The pressure produced by the expanding HTP ruptured the kerosene fuel tank in the torpedo and set off an explosion equal to 100–250 kilograms (220–550 lb) of TNT.

[17] The explosions blew a large hole in the hull and caused the first three compartments of the submarine to collapse, killing or incapacitating all but 23 of the 118 personnel on board.

On 21 August, Norwegian and Russian divers found 24 bodies in the ninth compartment, the turbine room at the stern of the boat.

Captain-lieutenant Dmitri Kolesnikov wrote a note listing the names of 23 sailors who were alive in the compartment after the boat sank.

However, the cartridge became contaminated with sea water and the resulting chemical reaction caused a flash fire which consumed the available oxygen.

[19] Russian President Vladimir Putin, though immediately informed of the tragedy, was told by the navy that they had the situation under control and that rescue was imminent.

Putin was only four months into his tenure as president, and the public and media were extremely critical of his decision to remain at a seaside resort.

"[22] A consortium formed by the Dutch companies Mammoet and Smit International[23] was awarded a contract by Russia to raise the vessel, excluding the bow.

As this tool had the potential to cause sparks which could ignite remaining pockets of reactive gases, such as hydrogen, the operation was executed with care.

Notwithstanding the navy's oft-stated position that a collision with a foreign vessel had triggered the event,[26] a report issued by the government attributed the disaster to a torpedo explosion caused when high-test peroxide (HTP), a form of highly concentrated hydrogen peroxide, leaked from a faulty weld in the torpedo's casing.

All of the 36 men in the command post located in the second compartment were immediately incapacitated by the blast wave and possibly killed.

[31] The heat caused the warheads of between five and seven additional torpedoes to detonate, creating an explosion equivalent to 2–3 tons of TNT[32] that measured 4.2 on the Richter magnitude scale on seismographs across Europe[33] and was detected as far away as Alaska.

Due to their inexperience and lack of training, compounded by incomplete inspections and oversight, and because the Kursk's crew followed faulty instructions when loading the practice torpedo, Ryazantsev believes they set off a chain of events that led to the explosion.