Cruises from Miami to Cozumel (Mexico) are very popular. Do you know that Cozumel is an island? It has a large coral reef that is great for snorkeling or scuba-diving adventures. Swim with dolphins. Drive an ATV around the island. Take an excursion to the mainland to see the ancient Mayan city of Tulum. Hit the duty-free shopping. Or relax on the white sand beaches.