Cumbo

We've decide to go on a holiday to Mexico. We have about 10 days (8 full and 2 when we fly from/to Miami). We want to
  - do diving in Cozumel,
  - snorkel with whale sharks and
  - some topside activities.
  
  Should we stay at Cozumel or can we go by boat from Playa del Carmen   every morning for dives (how long is the boat ride)? Should we pick an   all-inclusive resort with diving and meals included (i.e. are there some   recommended ones) or should we take a hotel and take dives separately?   Can you recommend nice dive companies/all inclusive resorts? We want a   reputable company because my girlfriend is a beginner.
  
  We also want to snorkel with whale sharks. Is Isla Mujeres the place to   go or do you recommend something else? Any companies recommended?
  
  How about topside activities? Is Cenote cave worth it? How about the Mayan ruins?
  
  I'd really appreciate the help!

Here are some of the shots I managed to take with my set in Lembeh Strait last August. This is my first trip with this set, so I'm still learning.

I'm using Canon PowerShot G12 in Canon WP-DC34 housing, Dyron 67 mm and 77 mm macro diopters and Inon D-2000. Any constructive criticism is greatly appreciated!

All the photos are here in Flickr.