This massive natural reserve is a UNESCO World Heritage site—the area has been home to a Mayan community since 600 B.C.—and it’s absolutely stunning. The best way to see it is with a half-day tour from Visit Sian Ka’an, which includes a guided visit to several Mayan archaeological sites (which are still undergoing restoration), a look at the trees and species that are endemic in this area, and a boat ride through the lagoon. Within the lagoon, you’ll get to float along the tributary in an absolutely ingenious “Mayan diaper”—a life jacket worn as shorts—and take in the natural wonder from the water. And if you’re lucky, you might even get the chance to walk into a Mayan ruin with a guide. The tour ends with a homemade lunch, either tender chicken or fish marinated in achiote, served with rice, beans, and fresh corn tortillas, all washed down with hibiscus juice—far better than the typical box lunch that most tours provide.