Our organic cotton undies can be worn in the sea, lakes, rivers and any other natural bodies of water. We recommend avoiding chlorinated pools or exposure to chemicals as this may damage the dye and fabric. Make sure to wash well after every use! Our team has used them when swimming outdoors and they are super comfy, retain their shape and don't come off when jumping in! If you're worried about them being see- through, our bralettes are double-lined ensuring ample coverage.