There are currently no traditional waterparks in Barbados. However, here are some alternatives:
Graeme Hall Sanctuary: This sanctuary serves as a home to migratory birds (in the winter) and local birds, fish and monkeys. You can purchase fish food at the café and feed the fish in the mangroves. Although the full reserve is not open to the public, ask at the café for directions to see the flamingoes.
Folkestone Marine Museum: This small museum has many interesting marine artifacts including massive whale bones and bottles retrieved from shipwrecks. Bring along your swimsuit for a dip in the lovely pools, picnic in the tropical gardens, and enjoy a stroll on the boardwalk. Children will also enjoy playing on the swings and slides in the playpark.