Puerto Aventuras is primarily a diving destination. The marina has two well-equipped dive shops — Dive Aventuras and Scubamex — offering reef dives, cenote dives, and PADI courses. The Caribbean reef just offshore is healthy, and the cenotes scattered through the jungle inland are genuinely spectacular: clear, cold, cathedral-like spaces that you can snorkel or dive through. The resort also has a 9-hole golf course set around the marina, and the marina itself has decent sport fishing for sailfish and mahi-mahi from November to April.
The Dolphin Discovery facility in the marina is the most controversial feature of Puerto Aventuras. It is popular with package tourists but draws criticism from marine conservationists; if you have concerns about captive cetaceans, skip it and spend the money on a cenote dive instead.