Cos'è marine? Cos'è marine? Of or relating to the sea: marine exploration. Native to, inhabiting, or formed by the sea: marine animals. Of or relating to shipping or maritime affairs. Of or relating to sea navigation; nautical: a marine chart. See Synonyms at nautical.Of or relating to troops that serve at sea as well as on land, specifically the U.S. Marine Corps.A soldier serving on a ship or at a naval installation.A member of the U.S. Marine Corps.The mercantile or naval ships or shipping fleet of a country.The governmental department in charge of naval affairs in some nations.A painting or photograph of the sea.