Marine (ocean), a general term for things relating to the sea or ocean
Marine (military), a soldier in a force under the authority of a navy, or in several cases (e.g. USMC), a soldier belonging to a force which was formerly under the authority of a navy
Royal Indian Marine, a colonial precursor of the Indian Navy that existed from 1892 to 1934
Merchant Marine, synonymous in (primarily) British usage with "Merchant Navy," a collective term for all of the merchant ships, shipping companies, and merchant mariners, usually of a particular country (see Ship transport)