Swimming pools, of course, are always lovely and inviting, but if you've ever seen a dark bottom pool you'll know that they have a little something extra, a deep and mysterious and enticing allure that other pools can't touch. Who could have known that the color of the bottom of a pool could matter so much? But it does — one of those little details that make such a big difference. A pool with a floor and sides in black or navy or what have you is warmed more easily by the sun, but also, paradoxically, seems cooler and deeper, and its surface reflects the surrounding landscape, for a mysterious and mirrorlike affect. Here are ten of our favorite examples.