We were just at Typhoon Lagoon in Sep-Oct with our 13 month old. We planned ahead and stopped at the Kissimmee Super Target on the way from the airport and bought a variety of things for him (lighter travel load) including the swim diapers. We did pack an infant inflatable "tube" for him as well. We were able to take him (with the tube & swim diaper) in the Lazy River which he loved. He was apprehensive at first as it's obviously far bigger than his duckie bath tub at home.
There are also some great areas (like little tide pools) between the beach and the big wave pool that have the small oasis-like islands to block waves. We took him through those as the water varies from 0 to 9 inch roughly (he was 31" at the time) and they have some small "tug boats" there to climb on.
There is a section to the South side of the big wave pool that has slides for young (older than toddler) kids. Just a bit further from that are foam crocodiles and small water fountains that our son loved. We have some great photos of him with the crocs as well! :sohappy:
Personal Note: It was very hot when we went and I think a nose full of the cold fountain water did him in as he had a slight head cold 2 days later. I'll take the blame as it's so hard to judge when to call it quits on the little one's first visit.
The Ketchakiddie Creek was really cool but only a few very tiny spots are designed for the very young. And as with any water park, walk with them and check out the crowd. You wouldn't want your little ones first attempt down a toddler water slide ruined by an agressive pre-schooler. (You know how little ones can get overly excited I'm sure.)
Personal Recommendation:wave:: Make sure you get one of the TL Photo Passes! The new photopass from the Lagoon is very small and have the springy wrist-bands. We used ours at all the parks. Also, in the Ketchakiddie Creek area, we found a photographer who was happy to take a few quick ones of our little guy. He was very photo-friendly that day and she ended up snapping over 30 pics as it was a slow day. We viewed them on-line after we got home from the trip. Our CM Photographer got a lot of beautiful pics we couldn't have captured ourselves at the park due to the nature of digital cameras and water. Well worth a few minutes of your time since it's all no obligation.