➡ to be registered to a specific country(the flag state) and use their flag while sailing.

➡ a piece of fabric, usually hung from a pole, to indicate a nationality of a vessel.

➡ the salt water that covers most of the earth's surface and surrounds its continents and islands

➡ a vehicle that can travel underwater, control its own movement and maintain its own life support.

➡ existing or located under the sea

➡ a liquid without colour, smell or taste that falls as rain, is in lakes, rivers and seas, and is used for drinking, washing, etc