Puzzle mats are a soft solution to hard surfaces making them perfect for the under side of pools! If you would like to give a softer bottom to your pool, consider setting up a puzzle mat under the ground cloth of your pool. Not only does this make a pool softer to stand and sit on, but also gives your pool liner a cool new design! The grooves from the puzzle pieces will show through the liner after a few days. This is something else to think about when buying for a child's pool. Alphabet letters and numbers can be arranged for an extra fun, and cool learning experience.