Naval means having to do with a navy. A naval officer, naval base, naval history.
It covers the service and its ships, where maritime covers the sea generally and marine covers the sea itself. Note the spelling against navel, which is the belly button and sounds identical — the two are among the most confused pairs in English. The Latin navis means a ship.
naval is a quality of relating to a navy.
Latin navalis comes from navis, a ship. Navy, navigate and nave come from the same ship.
Latin
nāvālis
Middle French
naval
Middle English
naval
English, today
naval
From Middle English naval, from Middle French naval, from Latin nāvālis; equivalent to navy + al.
Etymology from Wiktionary, CC BY-SA