Aquaworld is definitely one of the bigger and more reputable watersports companies in Cancun. From Dreams Cancun it would only be a 10-15 minute bus ride to get to their facility. A cab from there would probably take about the same amount of time, but it would cost a lot more. Aquaworld also does a lot of other stuff that everyone else may be interested in link para-sailing, waverunnners, jungle tour, snorkeling tours, diving certification classes, etc.
If you have any other questions, I would be glad to help.