While the words beach vacation usually call to mind a tropical white-sand beach studded with palm trees and lapped by turquoise waters, the truth is that the world’s beaches come in all shapes and sizes—some stranger than others. There are black, green, red, and even purple stretches of sand. Humans also add their own bizarre twists to the beaches of the world and have even tried to trump Mother Nature. Just look at the world’s largest swimming pool (pictured below), which runs alongside a gorgeous Pacific Ocean beach in Chile. Oh, what will they think up next?  … Details & Pictures