Why does the water in a wsimming pool stay cool on a hot sunny day?

Water in a swimming pool stays cool on a hot sunny day primarily due to its large volume, which absorbs heat more slowly than the surrounding air. Additionally, the evaporation of water from the pool's surface cools the remaining water, as evaporation requires energy and draws heat away. Factors like shade from trees or structures, as well as water circulation, can also help maintain cooler temperatures.