Sea water is salt water and can't be drunk directly.
Tips
usage
Pair with its opposite 淡水 ('fresh water') - both are everyday vocabulary for talking about water sources, fish, and ecosystems. 咸水鱼 = saltwater fish, 淡水鱼 = freshwater fish.
memory
咸 (xián) means 'salty' (one of the five basic tastes alongside 甜 sweet, 酸 sour, 苦 bitter, 辣 spicy). The traditional form 鹹 contains 鹵 (lǔ, 'salt'), making the meaning visible - the modern simplified form lost this clue.
