There are several places to catch ferries from Cancún to Isla Mujeres. Some ferries carry vehicles and passengers between Cancún's Punta Sam and Isla's dock; others carry passengers from Puerto Juárez.
Ultra Mar operates boats out of Gran Puerto Cancún every half hour from 5 am to 8 pm and then every half hour thereafter until 11:30 pm. Ferry departures from Puerto Juárez and Isla Mujeres can vary due to season or current demand—sometimes the last one leaves as late as midnight or as early as 9 PM. Be sure to ask for the current schedule. A round-trip ticket costs $7.
Ferries traveling directly from the Zona Hotelera run on more limited schedules. Ferries leave the Embarcadero dock for Isla Mujeres at 9:30, 11, 12:30, and 2 daily.
At Playa Tortugas, ferries leave for Isla at 9:30, 10:30, 11:30, 2:30, 3:30, and 5:30 daily. Round-trip fares start at $15 per person.
Embarcadero dock ferries (Blvd. Kukulcán, Km 4.5. 998/849-7515). Playa Tortugas ferries (Blvd. Kukulcán, Km 6.5).