It is not recommended to put a regular diaper under a swim diaper. Regular diapers are designed to absorb liquid, and when used in water, they become bulky, heavy, and may cause discomfort. Swim diapers are specifically designed to be used in water and provide both comfort and containment without unnecessary absorption. At Duraline Medical Products, we are committed to providing high-quality incontinence solutions that allow you to enjoy swimming and water activities without worry. Browse our collection of swimwear products and find the perfect fit for your needs. Swim with confidence and embrace the joy of the water!