Parasailing (paracaídas in Spanish) can be booked as a traditional one-person ride (with takeoff from the shore) or a two-person ride, in which you can take off from the boat or the water.
Prices and duration are fairly uniform: US$50–60 per person for a 10- to 12-minute ride. Look for independent operators on the beach, especially on Playa Ballenas, Playa Chac-Mool, and Playa Delfines [1]. Or sign up at Solo Buceo (Dreams Cancún Hotel, Blvd. Kukulkán Km. 9.5, tel. 998/883-3979, www.solobuceo.com [2], 9 a.m.–4:30 p.m. daily) or Aqua World (Blvd. Kukulcán Km. 15.2, tel. 998/848-8327, www.aquaworld.com.mx [3], 7 a.m.–8 p.m. daily).
Wave runners are rented on the same beaches where parasailing is pitched. Prices average US$55 for 30 minutes or US$100 for an hour; one or two people can ride at a time.
Banana boat rides are available at Playa Ballenas for around US$20 per person for a 20-minute ride. (Banana boats are those big, yellow rafts pulled behind motorboats.)
Links:
[1] http://www.moon.com/destinations/cancun-the-yucatan/cancun-cozumel-and-the-riviera-maya/cancun/sights/zona-hotelera-beaches
[2] http://www.solobuceo.com
[3] http://www.aquaworld.com.mx