I‘m not gonna bring it on as carry on but in my luggage
Well, if it's only for three days I really don't think you NEED a flat iron. Bring it if you want though. Bring: Swimmers. Towels Water shoes ( if it's a public lake there might be sharps on the bottom) TORCHES. Nothing is scarier than getting lost near a lake at night Shampoo and conditioner. Hope this helps