If you're looking for an inexpensive, fun toy for the pool or lake, Amazon has the Intex Explorer 2-Person Inflatable Boat marked down to just $13.22 right now.
I remember playing with these inflatable boats growing up. We camped at a trailer park every weekend from the time I was a baby and we used to live in the pond.
This boat has an inflatable floor for comfort and durability; a grab rope on the bow for pulling it around, welded oar locks (I don't believe there are oars included but we never used those) and two air chambers with double valves. It even includes a patch repair kit.
This little boat has great reviews (a lot of people apparently use it to store beer...) and one reviewer uses it as a kiddie pool! Genius! The big, high sides would be great. You can spend $30 on a kiddie pool that isn't super durable. Grab this for just $13.22.
Amazon ships orders of $25 or more free of charge.