In August 2000, the Russian Oscar II class submarine (which is the world’s largest class of cruise-missle submarine) Kursk sank in the Barents Sea when a leak of hydrogen peroxide in the forward torpedo room apparently led to the detonation of a torpedo warhead, which in turn triggered the explosion of around 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.Also from the Wikipedia article:
Despite a rescue attempt by British and Norwegian teams, all sailors and officers aboard Kursk were lost. A Dutch team later recovered 115 of the 118 dead, who were laid to rest in Russia. The fate of three bodies still unrecovered is debated, but it is generally accepted that they were lost in the explosion.
Most of the hull of the submarine, except the bow, was raised from the ocean floor by the Dutch salvage companies Smit International and Mammoet in the fall of 2001 and towed back to the Russian Navy’s Roslyakovo Shipyard…Russian President Vladmir Putin signed a decree ordering that all crewmembers will be bestowed the Order of Courage. The captain of Kursk, Gennady Lyachin, was awarded the title Hero of the Russian Federation.Thankfully, the international community recovered the Kursk, giving the families of the crew some sense of closure, and the submarine community some valuable information about how to prevent such a catastrophe from ever happening again.