Yes, you are permitted to bring a cooler into Disney's Blizzard Beach Water Park, but it must adhere to specific size and safety guidelines. The cooler must be smaller than 24" long x 15" wide x 18" high (the size that fits in a standard locker). Crucially, glass containers and alcoholic beverages are strictly prohibited. Additionally, for safety reasons related to water filtration, Disney does not allow loose ice or dry ice inside coolers; you must use re-freezable ice packs or "bagged ice" that remains sealed. Many families find this to be a major money-saver, as they can pack sandwiches, fruit, and bottled water to avoid the higher prices of theme park concessions. Note that while you can bring the cooler into the park, you cannot bring it into the actual water or onto the slides. There are numerous "picnic" areas and shaded spots with chairs where you can park your cooler for the day, or you can rent a large locker if you prefer to keep your snacks under lock and key while you enjoy the "Summit Plummet."