A swim vest is usually designed for children who are learning to swim. It provides less buoyancy than life jackets and puddle jumpers because it is a swimming aid rather than a life-saving device.Swim vests are designed to work with your child and help encourage proper swimming form. They are not designed to keep your child afloat. Your child can still swim underwater in a swim undershirt.Swim vests can go further than puddle jumpers because they allow your child to move his or her arms more freely, thus improving swimming technique in a more natural way. When should your child use a swim vest?Swim vests are perfect for children who are learning to swim. However, since they do not provide enough buoyancy to keep your child afloat, they may be better suited for children who already have a basic understanding of swimming technique and know how to tread waterIf your child can already swim, then a swim vest is ideal for use at the pool or beach. Some swim undershirts also offer UV protection, which is useful for spending the day at the beach or outdoor pool.