Encompassing swathes of tropical wilderness dotted with Maya temples, historic cities, and diverse wildlife, Petén in northern Guatemala is the largest state in the country. It’s also home to the Maya Biosphere Reserve—often referred to as the “third lung of the Earth.” This Maya heartland is best known as the home of Tikal, but there are plenty more things to do here, including visiting the pretty cities of Flores, Yaxhá, and Aguateca, and hiking to El Mirador, a 2,500-year-old city buried so deep in the jungle it’s only accessible via 5-day trek or helicopter ride.