To sink or submerge — to go down into a liquid or to descend beneath the surface (e.g., a ship, object).
古い船が嵐で海に沈んだ。
The old ship sank into the sea during the storm.
コインを池に落としてしまい、底に沈んでいった。
I dropped a coin into the pond and it sank to the bottom.
岩がゆっくりと湖の底に沈んだ。
The rock slowly sank to the bottom of the lake.
To go down or set (e.g., the sun) — to descend below the horizon or decrease in height.
夕日が海に沈んで、空が赤く染まった。
The sunset went down into the sea and the sky turned red.
日はゆっくりと沈み、夜の静けさが訪れた。
The sun slowly set, and the calm of night arrived.
月は西の空に沈み始めた。
The moon began to set in the western sky.
To feel depressed or down — to become subdued, heavy-hearted, or gloomy.
試験に落ちてから彼はずっと沈んでいる。
He's been down since he failed the exam.
雨が続くと気持ちが沈みがちになる人もいる。
Some people tend to feel down when the rain continues.
会議の雰囲気が沈んで、誰も発言しなくなった。
The mood in the meeting became subdued, and no one spoke up.