On April 12th, 1970, one day after the launch of Apollo 13 and two days before Houston was notified of a problem, a Soviet November-class SSN sank in the Bay of Biscay. Four days earlier, there had been a series of fires on board the sub, and it had been taken in tow, in an effort to bring it back to a Northern Fleet port. Unfortunately for the K-8 and her crew, bad weather, and likely bad damage control design, caused it to sink in 15,000 feet of water, carrying her reactor and several of her nuclear-tipped torpedoes.
I was at the Military Airlift Command I&W Center at the time, and although it wasn’t our primary area of responsibility, we followed the misadventures of the K-8 with some interest. The sub went down about 175NM west of France’s Brittany Peninsula, and 260NM south of Ireland, and for years afterwards, the Soviets kept a ship loitering in the vicinity, to prevent anyone (read: U.S.) from attempting to salvage the wreck. This became a more or less permanent feature, to the point that it became an oceanic landmark. The Soviet cruiser transiting to the Mediterranean is currently located 200NM south of Lost November was a typical phrase in the Naval Intelligence reports of the day.