Tulum's signature attraction is the Maya ruins — but the surrounding landscape offers an equally compelling programme. The second-largest barrier reef in the world lies just offshore, making for outstanding snorkelling and diving, while the jungle conceals hundreds of kilometres of flooded limestone caverns: the cenotes that draw divers from around the world for an experience unlike anything else on earth. Combine the ruins, a cenote swim, and an afternoon on the beach and you have one of the best days Mexico can offer.