On August 12, 2000, at 11:28 local time, an explosion occurred aboard the Kursk, a nuclear-powered submarine of the Oscar II class, during preparation for a test firing in the Barents Sea. The Kursk was 154 meters long, about the length of two large aircraft carriers. Its double hull and nine watertight compartments gave it a reputation as unsinkable. The incident began with a leak of hydrogen peroxide in an exercise torpedo 65-76A. The final report by the Russian navy concluded that a 65-type torpedo powered by this fuel had failed. Approximately two minutes later (135 seconds), the warheads in the forward compartment detonated, with the second explosion equivalent to 3 to 7 tons of TNT. Norwegian seismographs recorded the shock wave. The hull was split open, and the first three compartments collapsed. The 36 men in the command post, in the second compartment, were likely killed instantly, and a sailor's body was found embedded in the ceiling. Further back, the sailors in the reactor compartment locked themselves in to prevent a possible leak. The reactors shut down automatically, and no radioactive leakage was detected. Compartment 9, six hours in the dark, was designed for evacuation and was the part of the submarine farthest from the explosion. It measured approximately 8 meters by 3, with icy water up to the waist and limited oxygen. Dmitri Kolesnikov, 27 years old, son of a submariner from Saint Petersburg, commanded the turbine section. Nearly two hours after the explosion, he wrote a note listing the names of the 23 sailors still alive. It read "I am writing blindfolded," as well as two numbers, 13 and 5, without explanation; the rest, private, has not been made public. As the hours passed, oxygen became scarce. The men attempted to replace a chemical cartridge of potassium superoxide, but it fell into water mixed with oil and exploded upon contact. The fire killed several sailors, then a sudden fire consumed the remaining oxygen and asphyxiated the last survivors. Analysts estimate the group held out for more than six hours. For comparison, it is longer than a school day, spent in the dark, at a depth of 354 feet (approximately 108 meters). Three sailors had burns on the upper part of their bodies, likely protecting others. The British and Norwegian navies offered their assistance, but Russia initially refused all help. The rescue submarine AS-34, repaired, was launched only on August 14 at 5 o'clock, and the Russian equipment failed to dock with the hatch. Meanwhile, the Russian admiralty repeated to the public that the majority of the crew died within minutes. On August 21, Norwegian divers finally opened the hatch, nine days after the accident. Norwegian and Russian divers discovered 24 bodies in compartment 9, one more than on Kolesnikov's list. The 118 crew members were dead. The Dutch company Mammoet won the salvage contract in May 2001. In three months, it and its subcontractors designed, manufactured, and installed more than 3,000 tons of custom equipment. The two explosions had not pierced the reactors, which avoided a nuclear meltdown and widespread contamination of the Barents Sea. On the family side, the widow of Kolesnikov, Olga, a teacher, said she wanted to read her husband's letter. The navy, however, kept the main text for itself.