Stadium Swim provides large towels, so there’s no need to bring your own. They also sell swim essentials if you happen to forget something, including:
Hats
SPF 50 sunblock
SPF lip balm
Sunglasses
Waterproof phone cases
Swimwear
Beach totes
Of course, you can always bring these items with you. Just know there is a security checkpoint before entering Stadium Swim, and all prohibited items, including controlled substances and outside food or drinks, will not be allowed.