I think it depends on the type of ship you are on at the time. On something like an aircraft carrier, watching flight ops was really cool. It always amazed me how much of an organized disaster flight ops were. It's not like an airport where there is plenty of breathing room as aircraft taxi to and from the runway. There really isn't that much of a tarmac on a carrier. Watching the aircraft launch and recover was really cool. Watch the shooters perform their "dance" on the flight deck as they gave the all clear to launch was neat. During night ops, we used to try to guess the type of aircraft that was landing off the configuration of the lights on the aircraft. We even got good at guessing the type of aircraft just off the sound of the engines.

On a small ship, night time was the greatest thing out at sea. To just look up and see ALL the stars out on a cloudless night was great. Hearing nothing but the lapping of the waves and the distant sound of the engines was claming (assuming the waves weren't that big).