The dive operation there is run by aquaworld. If you don't want to dive with them, then I would suggest going to puerto morelos (there are a couple of dive ops there), or playa (a bit further, but more options).
here's a list of shops in pto. morelos I just copied from a website.. don't tell anybody.
Almost Heaven Adventures - Dive Shop in Puerto Morelos
Scuba diving, snorkel trips, fishing trips and jungle tours. Tel: 998 871 0230
Location: North side of Puerto Morelos on the main street, Rojo Gomez and La Ceiba del Mar Hotel and Spa Open 8:00 am - 5:00 pm, open daily
Aquanauts Dive Adventures Aquanauts Dive Adventures - Dive Shop in Puerto Morelos A
Guided coral reef dives, cenote explorations, excursions to Cozumel, PADI certifications classes, snorkeling tours and fishing expeditions
Location: Hotel Hacienda Morelos Suite # 107. Av. Rafael E. Melgar
Aquanauts Dive Adventures accepts credit cards Accepts credit cards. Open 8:00 am - 4:30 pm, Open daily
Dive In Puerto Morelos Dive In Puerto Morelos - Dive Shop in Puerto Morelos
Scuba diving, snorkelling, reef/fresh water, English/Spanish speaking, experienced high service level crew - wreck dives, reef dives, PADI certifications
Location: Ave Rojo Gomez #14 sm2 mz 5 lo 15, N of the park square on left
Dive In Puerto Morelos accepts credit cards Accepts credit cards. Open 8:00 am - 5:00 pm, open daily
Marina Dive Center Marina Dive Center - Dive Shop in Puerto Morelos
To teach and guide divers in a relaxed and personal atmosphere... It is just our way of working. After all diving is all about fun!
Location: Marina El Cid, in front of the protected marine park of Puerto Morelos
Marina Dive Center accepts credit cards Accepts credit cards.
Mystic Diving - Dive Shop in Puerto Morelos
Mystic diving offers a professional and qualified staff. Certified guides, fast and comfortable boats. Flexible dive times. PADI and NAUI instructors. For reservations call country code 52, 998-871-0634
Location: Ave Rafael E Melgar #2, Sm. 1
Mystic Diving accepts credit cards Accepts credit cards. Open 8:00 am - 6:00 pm , daily.
Wet Set Diving Adventure Wet Set Diving Adventure - Dive Shop in Puerto Morelos
Wet Set Water Adventures of Mexico offers scuba diving and PADI scuba instruction,snorkeling and fishing.
Location: Ojo de Agua Hotel
Wet Set Diving Adventure accepts credit cards Accepts credit cards.