If you think this particular blue ribbon is a perennial favorite, you'd be right. If you believe we choose it because of the coral grottoes, underwater caves, and glorious waterfalls, you'd be absolutely correct. And if you surmise that the porticos and loggias provide us with some much-needed shade during times of sun, then yes, you're in the know. But the real reason we pick this 820,000-gallon, spring-fed pool as the most refreshing place for Miamians to bathe is a caveat: No children under the age of three are allowed. Which means -- you guessed it -- there's no P in the V.