Are swim diapers required for children three years of age and younger? Yes, swim diapers are required for children three years of age and younger. Swim diapers are available for purchase at the Water Park in the Surf Shop. Was this article helpful? Related articles Are cotton shirts allowed on the slides? Are rash guards allowed? When is the best time to visit LEGOLAND Water Park? Are strollers allowed into the Water Park? My child used to be able to ride his/her favorite ride, now they cannot, why?