Translation guide
The word 'seawater' refers to water from the sea. In Japanese, the most common and natural equivalent is 海水 (かいすい). This guide covers how to express the concept in various contexts, from everyday conversation to technical usage.
海水
seawater
Referring to seawater in general, as a substance or body of water.
The standard, neutral word for seawater. Used in all contexts.
Literally 'water of the sea'. More descriptive, often used in explanatory or poetic contexts.
海の水はなぜ青いの？
Why is seawater blue?
Referring to seawater for desalination, cooling, or scientific purposes.
Expressing concepts related to seawater, such as seawater temperature or seawater fish.
Prefix 海水 to form compounds like 海水温 (seawater temperature), 海水魚 (seawater fish).
海水温が上昇している。
Seawater temperatures are rising.
While seawater is salty, the general term for salt water (e.g., for gargling) is 塩水 (しおみず). Use 海水 specifically for water from the sea.