Some resorts tout their luxurious rooms; others, their fantastic food options. At San Alfonso Del Mar, it's all about the pool. Boasting the world's largest and deepest swimming pool — it's larger than 20 Olympic-size pools, 115 feet deep at its deepest, and holds 66 million gallons of water — this resort offers multiple buildings along its fake shores. Every apartment offers a balcony with ocean views — the pool is right on the shoreline — but odds are you won't be spending much time in your room, thanks to the various on-site clubs, the sailing, scuba diving, kayaking, and waterslides at the pool, and the on-site ocean aquarium. Raining outside? Not to worry — there's a temperature-controlled "beach" in the pool that's encased in a glass pyramid.