For the water park:
goggles and such
head sets /headphonesPower strips and extension cords might be needed, or not. If people with plenty of room and a spare power strip could put them in the car just in case, that would be great. Mark them, maybe.
(I don't know what you'll need, but whatever it is, bring it.)
I'm bringing:One request: Please Do Not bring "Cards Against Humanity," or if you do, keep it in your room. Too disturbing for mixed-age, mixed-group.ChronologyIf people have other board games that can be played by a large and variable number of people, that would be good.
Wise and Otherwise
Extra set of car keys, if you're driving
Electronics and paraphernalia
Camera, extra batteries, chargers
Computer (if you do that sort of thing when travelling), cords, chargers
Food for the rooms (we can't have it in the conference center, but stock your car and room, maybe).