 Operation Crossroads began with the first blast ( Test Able ) , an air burst on 1 July 1946 ; Nagato was not close to ground zero and was only lightly damaged . For Test Baker , an underwater explosion , the ship was positioned closer to ground zero . Nagato rode out the tsunami of water from the explosion with little apparent damage ; she had a slight starboard list of two degrees after the tsunami dissipated . A more thorough assessment could not be made because she was dangerously radioactive . Her list gradually increased over the next five days and she capsized during the night of 29 / 30 July . Opened to divers in 1996 , The Times has named Nagato as one of the top 10 wreck diving sites in the world . 
