沖
おき · oki · JLPT N3 · noun
sea
🌊⛵ 沖 = 氵 water + 中 middle: out in the middle of the water
沖 (oki) is the water far from shore, past where the waves break. You already know it from 沖縄 Okinawa, the islands out in the open sea. Phrase: 沖に出る, to head out to sea.