You sound like the kind of folks who know how to enjoy AC best : )

There is a little bit of "snorkel off the beach" at Ramon's pier. But to really enjoy the reef fully, do the tours to Hol Chan/Shark Ray Alley, etc. Alfonso Graniel is a fantastic guide. Very knowledgeble, safety concious and LOTS of fun. Your teens will love him.

There are so many wonderful and varied places to eat. You can walk down the streets in San Pedro and find little shops with local flavors. Chicken stews, burritos, seafood, cocoanut rice, YUM! I highly recommend AliBaba's for Greek and you have to try the beach BBQ at BC's (Sundays) or Holiday Hotel (Wednesdays).

Talk to the locals and tourists alike, you are gonna love this place!