I would have said something had I had the chance, but I was in the wave pool, and I would not have even noticed except bell had just rung, and I turned around to find DS..
I went by myself to Stormalong Bay and left my bag and towels on a chair and nothing was moved or touched. I swam for awhile and when I came back all was as it was before.
I think I would feel more vulnerable to theft and people just walking up and using your towels at the Water Parks, but I would go there with hubby and we would take turns in the water and sunning. So that way there would always be one of us at the chairs. All the real valuables? Into a locker. No question. I would not take stuff in a bag to the Park that I was afraid of losing, just some reading material, lotion, and like I said any money or passes or room keys go into the locker. That way you don't risk losing somthing you can't live without.
Magazines and books can be replaced. And if I saw people grab up and use my towels off my chair that I rented? I would certainly say something to them. But that is just me. Or just bring some towels you don't care about losing. We have some of those floating around the house....great idea to pack them for the water park.
Have fun, don't take anything you don't want to lose and use the lockers!
ariel