YSK: If you are at the beach and are being pulled by a current into deeper water, swim parallel to the beach to the right or left, toward the white caps of the breaking waves to free yourself from the riptide.
from /r/YouShouldKnow
YSK: 海岸にいて、海流に引っ張られて水深が深くなっているときは、海岸と平行に右か左に泳ぎ、砕けた波の白い帽子の方に向かって泳ぐと、潮の流れから解放されます。