I agree, great book! And it has already been made into a good documentary, called "The Search for HItler's Lost Sub"—or something like that. Those two divers have actually become quite famous off that wreck, enjoying an ongoing successful wreck-diving TV show in recent years as a result.
(Your SCR Sub Books editor)
Sure writing is easy: just sit staring at a blank page until the drops of blood start forming on your forehead.