How to say "submarine" in Japanese

• サブマリンCommon
  nounThe katakana loanword for the underwater vessel. It refers to the same craft as 潜水艦, the difference between the two being mainly one of written form — borrowed katakana versus kanji.
  サブマリンのペリスコープが水中すいちゅうからにょっきり突き出つきでていた。↗

  The submarine's periscope was sticking right out of the water.
• 潜水艦せんすいかんCommon
  nounA submarine as a vessel: a ship capable of operating underwater. Like サブマリン it names the craft itself, written in kanji rather than borrowed katakana.
  潜水艦せんすいかんは沈しずんで二に度どと浮上ふじょうしなかった。↗

  The submarine sank, never to rise again.
• 海底かいていCommon
  prenominal modifierThe bottom of the sea. Its English match 'submarine' is only the adjective 'undersea', so use it where English says 'undersea', never for the vessel.

For the underwater vessel, 「サブマリン」 and 潜水艦 are both used — the katakana loanword and the kanji term respectively; 海底 belongs to the adjective sense 'undersea' and never names the ship.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• サブマリンsubmarine
• 潜水艦せんすいかんsubmarine
• ＵボートユーボートU-boat
• 潜水艇せんすいていsubmersible
• 海底かいていundersea