In the first act of Crimson Tide, a couple of sailors are having a discussion about characters in all-time great submarine movies like Run Silent, Run Deep and The Enemy Below. Tony Scott's 1995 thriller is now among these submarine classics, and yet it's an incredibly different kind of a sub movie. Most submarine movies are about the naval warfare. They play with navigation, timing, and precision to fight off an enemy. But Crimson Tide doesn't really have an enemy. There's an external force—Russian nationalists who are threatening to steal nuclear missile launch codes—…