Howdy Pam!
We could not live without our backpack!!
We always travel with a backpack (and in our case a diaper bag as well). We put bottles of water, snacks, sunscreen, a small first aid kit, our cameras, tissues, and hand sanitizer in ours.
Here is a list of prohibited items.
Backpacks are allowed on rides. Thrill rides often have an area to put the bag on with you, if not, I remove the backpack, place it on the floor of the ride compartment and stick my foot through one of the straps. Other rides you can just place it on the seat with you or on the floor.
Have a magical vacation!
Amanda