When choosing goggles, consider three factors: eye socket shape, face width, and nose height/width. Buy goggles only if you have tried them on. To test, put the goggles on and gently press them against your eyes, but do not secure the strap behind your head (let the strap hang under your chin) and release the goggles. If a vacuum forms, the goggles will stay in place and not let water in while swimming. If the goggles immediately fall off or only one side stays in place, they will leak water.