and for some actual war time footage of both IJN and USN subs, including long range missions of IJN to Germany (and some great footage of the Graf Spee, German U boats) including on board action shots of US boats...
enjoy..(these are in the public domain)
http://www.archive.org/details/VAS_1...Southern_Cross
http://www.archive.org/details/VAS_21_Full_Fathom_Five