What kind of snacks and drinks are allowed? Size cooler or backpack?

Yes. They allow a backpack size cooler. Although we did see people with large size coolers

I was just there. They do allow coolers but I can't be for sure on size. They have size and dimension right outside the gate. They also allow you to bring snacks and drinks.

You can't bring drinks or snacks into the park. No coolers at all.

I was able to bring snacks and drinks

When I went, no coolers were allowed. No snacks and drinks were allowed either, they check bags as the entrance