One side is guarded by the waterfall and slide , one side by the courtyard leading to the Preview Center/Spa/Fitness Center, one side by the snack bar (with fencing) and one side by a picket fence.
While it's still possible for a young child to wander off (towards the preview center or up the steps towards Artist's Palette), the pool is certainly surrounded by fencing to discourage little ones from straying into traffic areas easily.
<img width="300"src="http://disneydoc.homestead.com/files/SSRMay04_057.jpg">