Light to medium flow: Yes. When you are in the water, the blood cannot leave your body because of the water pressure. When you come out of the water, the blood will naturally escape and flow into your bathing suit (replacing the water in the absorbent part). Blood contains iron and is therefore heavier than water, which is why it settles to the bottom of your period swimwear.
If you have a medium to heavy flow, the period beachwear is best to be used as additional protection to the tampon or menstrual cup. In this case, we do not recommend wearing the period beachwear on its own when swimming.