One-Piece Swimsuit

A one-piece works because the fabric runs uninterrupted from shoulder to hip, so the tension is spread across the whole torso instead of being carried at a waistband. That is what keeps it in place when a wave arrives or a dive ends, and it is why a one-piece is the swimsuit people choose when they intend to actually swim rather than sit. The trade is that a single panel has to fit the length of your torso as well as its width, so check the rise before the size, since a suit that is right around and too short between shoulder and hip will pull all day.