You can't use a normal cloth nappy for swimming as it will absorb too much water and weigh baby down. Disposable nappies do the same. Reusable swim nappies are traditional swimming pants. These are machine washable and have a soft lining, leg cuffs and waistband to prevent solids getting into the pool. Reusable swim nappies are designed to catch poos and let the wee pass through.