Imse Vimse Swim Diaper (Green Fish) is smooth and safe . No extra insert or diaper needed. Thanks to very soft and smooth elastic around the waist and legs, your child can move freely in the water. ImseVimse swim diapers consist of a layer of soft fabric that is leakproof in case of accidents and a stretchy bathing costume fabric on the outside. Snap fastenings make it easy to pull the diapers on and take them off, even when wet.