It's inside Studios and it's free after entered the Park. If you don't know where it's inside, check the map OR ask one of the Staff there and they will point you in the right direction. Have Fun and don't forget to Bring Your Own Towels or you will be paying $24.99 for thin towel. (Thick Towel sells for around $10+ at Costco...)
Inside Universal Studios. No need to get extra ticket to use it.
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