Directly derived:
* Marine: (adjective) relating to the sea or seafaring; (noun) a sailor in the navy
* Mariner: (noun) a sailor; a seafarer
* Marines: (noun) soldiers who fight at sea or on land, especially those belonging to the United States Marine Corps
Related words:
* Maritime: (adjective) relating to the sea or navigation; maritime law
* Marina: (noun) a harbor or dock for pleasure boats
* Mariculture: (noun) the farming of marine organisms
* Marine biology: (noun) the study of marine life
* Marine life: (noun) the plants and animals that live in the sea
* Marine ecosystem: (noun) a community of organisms and their environment in the sea
* Marine environment: (noun) the physical and chemical conditions of the sea
* Marine pollution: (noun) the contamination of the sea by harmful substances
Other words with similar meanings:
* Oceanic: (adjective) relating to the ocean
* Nautical: (adjective) relating to ships or sailing
* Aquamarine: (noun) a bluish-green gemstone
* Submarine: (noun) a vessel that travels underwater
* Aquarium: (noun) a tank or building where aquatic animals are kept
* Seafaring: (adjective) relating to sailing or sea travel
This is not an exhaustive list, but it provides a good starting point for exploring words with the root "marine."