潮
In the distance, you see a rock outcropping. It piques your curiosity, so you shed your clothes and begin to swim out to it. The water is cold and salty, but the rocks aren't far, and not long after, you reach it. It's smaller than you expected, with some tide pools scattered throughout low cliffs, and you are sprayed time after time by crashing waves. Nonetheless, you find yourself amused by the small creatures scuttling from pool to pool, and you lose track of the time.
Eventually, the tide rises enough so that you're always walking in a puddle, and you look back towards the beach you swam from, intending on returning to shore. But the sand you had walked on moments before is now all submerged, and now, only rocks meet your eyes.