Cancun treats every day as a holiday, but also plans a few organized events throughout the year. The biggest event is Carnaval, a joyous, usually drunken celebration held in February right before Lent's period of fasting and penitence. Inmaculada Concepcion is a religious festival held on Isla Mujeres in December.
Day 1: Water
You're brilliantly positioned to hit the water at Cancun. Jump in with a Jungle Speedboat Tour across lagoons and coral reefs, with time to stop for a snorkel adventure to explore the magical underwater world.
Day 2: Fun
Budding pirates and romantics alike will love the Captain Hook Cruise aboard a Spanish galleon. The Caribbean Carnival on Isla Mujeres takes you on an early-evening cruise to the island, with a buffet dinner and Caribbean show.
Day 3: Adventure
Chichen Itza isn't the only day-trip destination from Cancun, though those Mayan archaeological ruins are mighty popular.