You need shoes that can get wet. Otherwise I don't know how you are going to get around. I mean you hike to the top of the slide if you leave your sneaks there then you have to hike back.....
The one time I went without water shoes about 30 minutes into the visit I was at the store there buying expensive Disney waters shoes
Im of the opposite school of others here. I bought some water shoes and they were so uncomfortable so I never wore them over 20 minutes. I have brought sandles in the past too but every time i go I end up going bare foot. I have been in July, May and August twice and mostly Typhoon Lagon and I always go barefoot and never have a problem. (Ive only been to Blizzard Beach twice and never wore them there either) I wont say it isnt hot in spots but I never felt too hot to walk anywhere.
Water shoes are not required, but I wear them. I have some Nike Straprunners, that are very lightweight. As previously posted, some areas of the parks can really make your feet raw. I cannot wear the enclosed water-sock type shoes as they make my feet raw, too. If you go on any of the big slides, you have to remove everything, except your swimsuit!! You can take off your shoes and hold them in front of you on the way down.
Dh and I always use our water shoes especially in the lazy rivers, we are tall and typhoon lagoon really scrapes the bottom, in the wave pool there he takes them off. Our 3 ds however, just go around barefoot.
DD wont' go to any water park or such w/o pool shoes any more. If the cement is at all rough, and it usually is somewhat rough just for traction, her feet get rubbed up pretty fast - NOT what I want to have happen if we've got park days left and will need to be walking.