Japan’s WW2 submersible aircraft carrier has been found on the ocean floor: http://t.co/aOrCfA05E9

— Noah Smith (@Noahpinion) December 3, 2013

They found the I-400. Submarine aircraft carrier. Would have been world-changing in a pre-sonar era, as-is they probably would have stuck out like enormous sore thumbs (barring better countermeasures than the IJN had, IMO).