also: うなぞこ
bottom of the ocean; seafloor; seabed
Refers to the physical bottom of the sea or ocean. Common in scientific, geographical, and everyday contexts.
海底にはまだ多くの謎が残っている。
Many mysteries still remain on the ocean floor.
The ship sank to the bottom of the sea.
noun-modifying (irregular)
undersea; submarine
Prenominal use, modifying nouns to mean 'under the sea' or 'submarine'. Common in compound terms like 海底ケーブル (submarine cable) or 海底火山 (submarine volcano).
海底ケーブルがインターネット通信を支えている。
Submarine cables support internet communication.
海底火山の噴火で新しい島ができた。
A new island was formed by the eruption of a submarine volcano.
The ship sank to the bottom of the sea in the storm.
The research team explored the seafloor using an unmanned submersible.
The treasure is said to still lie at the bottom of the sea.
Ancient artifacts were discovered on the seafloor.
seabed exploration; submarine prospecting
fruitless effort; wasting time on an impossible task