Bikini Bite is the #1 No-Slip Suit Fastener available. Used by bodybuilders world-wide. It is a roll-on, doesn't stain fabric, cleans off with soap and water but keeps your suit where you want it. Some of our suits may move and expose more than you want. Bikini Bite can help.
Note - this doesn't mean you can play volleyball in a suit with maximum exposure and have it stay in place but sitting and walking the beach shouldn't be an issue.