The coastlines of Mexico harbor many stretches of beaches that are frequented by sun bathers and other visitors. On the Yucatán peninsula, one of the most popular beach destinations is the resort town of Cancún, especially among university students during spring break. Just offshore is the beach island of Isla Mujeres, and to the east is the Isla Holbox. To the south of Cancun is the coastal strip called Riviera Maya which includes the beach town of Playa del Carmen and the ecological parks of Xcaret and Xel-Há. A day trip to the south of Cancún is the historic port of Tulum. In addition to its beaches, the town of Tulum is notable for its cliff-side Mayan ruins.