Sorry - only know of one beach really well because that is the one we always recommend for snorkeling and scuba diving. That is Chankannaab Park. It is a marine park and has open air restaurants that I have eaten at, lagoon with hiking trails around, minature golf, the Dolphin Encounter/Swim, snorkeling and scuba diving and much much more - there are also some shopps there. It is a $10 cab ride and $12 per person to get in. Extra for the rest but it is a big beach with umbrellas and chairs already there and very clean white sand. We love the diving there so when we have others with us and want to all go to the same place we go there so we can dive while they shop, eat, drink and play.
I do not remember ever seeing parasailing there though sorry. A lot of times the taxi drivers can help and actually I bet if you do a google search on Cozumel beaches you will find a lot because the island is becoming another Cancun and getiing way too over delveloped.. Debbie