下海
xià hǎi · HSK 7
to take the plunge
🌊 下海 = down (下) + sea (海); go down into the water = take the plunge
Literally to go down into the sea to swim. Figuratively to take the plunge — leaving a safe job for risky business, the same nerve it takes to wade off a beach into deep water.
下 — horizontal line 一 + mark below
下 is an indicative character: a long horizontal line represents a reference level, and a shorter stroke placed beneath it points to the area below. The original meaning 'below, down' comes directly from this spatial diagram, and it later extended to verbs like 'descend' and 'lower'.
海 — water radical 氵 + 每 (phonetic)
海 is a phono-semantic compound. The 氵 (water) radical signals the meaning—a vast body of water—while 每 supplies the sound. Originally referring to the sea or ocean, it later extended figuratively to mean 'vast' or 'a great quantity,' as in 人海 (a sea of people).