ちょっと一杯[chottoippai] let's have a quick drink
ばつ一[batsuichi] being once divorced
一向[hitaburu] nothing but
サラダ一皿[saradahitosara] plate of salad

安全第一[anzendaiichi] safety first
一か八か[ichikabachika] sink or swim
一っ走り[hitoppashiri] spin (as in 'take a car for a spin')
一つ一つ[hitotsuhitotsu] one-by-one

海鷂魚[ei] ray (fish)
井の中の蛙大海を知らず[inonakanokawazutaikaiwoshirazu] parochial
一天四海[ittenshikai] the world
雲海[unkai] sea of clouds
沿海[enkai] coast

遠海[enkai] deep sea
黄海[koukai] Yellow Sea
温海[atsumi] warm sea
海の幸[uminosachi] seafood

滄海[soukai] blue waters
滄海一滴[soukaiitteki] a drop in the ocean (bucket)
滄海桑田[soukaisouden] The word is a scene of constant changes (as the blue sea changing into a mulberry field). (Chinese legend)

桑田滄海[soudensoukai] The word is a scene of constant changes (as a mulberry field changing into a blue sea). (Chinese legend)
滄溟[soumei] great blue sea
滄浪[sourou] blue waves

一滴[itteki] drop (of fluid)
雨滴[uteki] raindrops
水滴[suiteki] drop of water
滴り[shitatari] dripping
滴る[shitataru] to drip

滴下[tekika] drip
滴定量[tekiteiryou] titer
点滴[tenteki] raindrops
点滴器[tentekiki] dropper