The Tapu Tapu is very similar to the Disney Magic Band in that it allows you to save your spot in line, pay for food and merchandise at Universal’s Volcano Bay Waterpark.
The Tapu Tapu also allows you to “Tap tu” open lockers and play interactive games within the waterpark.
This is a really nice perk at the park so that you do not have to worry about your wallet and/or keys getting wet or lost while experiencing the attractions within the waterpark.