submarine
sub-ma-rine
noun
A vessel capable of independent operation underwater, typically for military purposes.
"The nuclear submarine patrolled the deep waters."
adjective
Existing, occurring, or used beneath the surface of the sea.
"Divers explored the submarine caves."
Thesaurus
Synonyms: submarine sandwich, bomber, wedge, hoagie, hero sandwich, Italian sandwich, sub, Cuban sandwich, poor boy, torpedo, hoagy, hero