Hidden deep underwater is the untold story of how the Nazis waged a secret war across the world’s oceans. ➡ Subscribe: http://bit.ly/NatGeoSubscribe ➡ Get more Nat Geo Full Episodes: https://youtube.com/playlist?list=PLivjPDlt6ApSiD2mk9Ngp-5dZ9CDDn72O ➡ Get more Nat Geo Wild Full Episodes: #kevin1230san