Tulum is the rare beach destination with genuine ancient ruins right on the sand — the Tulum archaeological site sits on a clifftop directly above turquoise Caribbean water, making it one of the most photogenic ruins anywhere in Mexico. Beyond the ruins, Tulum's wider appeal is the combination of beach time, cenote diving (swimming in freshwater sinkholes that connect to vast underground cave systems), and a beach-town atmosphere that's become genuinely fashionable without yet losing the laid-back character that built its reputation in the first place.