He seemed to enjoy it, or at least it didn't scare him. He was very calm and quiet the whole time. We think it was because he missed his afternoon nap and was very tired. Towards the end of the adventure he was falling asleep on our shoulders.
We only kept him in the water for 10 minutes or so at a time and we only stayed 30 minutes all together. The internet said that was the safe way to get them started in the pool.
And like most people, after a day at the pool, we came home and River took a loooong deep nap. There is something about the sunshine and water that just wears you out.
Here are some pics: