海

artificial island city; floating city

Often translated as "sea slug" in anglicized haikus

sea cucumber (Holothuroidea spp.)

Astronomy

Neptune (planet)

flowering crab apple (Malus halliana)

Kaido crab apple (Malus micromalus)

Chinese flowering apple (Malus spectabilis)

Siberian crab apple (Malus baccata)

aronia (flower)

Colloquial

China Coast Guard

Abbreviation

maritime security; coast guard

cuisine with fresh seafoods

submarine volcano

below sea level; undersea; beneath the waves

sea fishing

Common noun

sea and mountains

Nouns which may take the genitive case particle 'no'

deep (indebtedness, love, etc.); immense

Department of the Navy

shipping industry; shipping business; marine transportation business

Abbreviation

Japan Coast Guard; JCG

port; seaport

land and sea

Abbreviation

Maritime Self-Defense Force

pirated edition; pirated version; bootleg copy

opening of the beachgoing season

advance (e.g. of Japanese exports) into overseas markets

the whole country

Common noun

marine product

Nouns which may take the genitive case particle 'no'

marine (e.g. product, animal etc.)

Haiti

dolphin (or other small toothed whales, incl. porpoises, belugas, etc.)

swim trunks