Recently finished "Silent Running" by James Calvert and started "The War Below" by James Scott. Before those, I plowed through "The Depths of Courage" by Flint Whitlock and John R. Smith.
That's for non-fiction. For fiction, I periodically leaf through the works of Ned Beach, Harry Homewood, and P.T. Deutermann ("The Iceman" was one hell of a page turner if you haven't caught it yet). Now I'm working on my own!