We brought our previously broken in crocs with us to WDW and on the 1st day of our trip youngest DD's strap ripped on one of hers so there we were in the middle of MGM and I had to walk into a shop and buy new crocs for both of them. They put them on and walked all day and for the rest of the week in their brand new crocs with no problem. I would bring tennis shoes just to be safe, but I doubt they will want to wear them instead of their crocs but you never know about blisters.