VHS, agree with Misty
Just came back from staying at the Barcelo for our 2nd time. Both times I dove with Aquanauts at nearby Puerto Aventuras instead of Dressels on site. Taxi is ~ 11$ one way from Barcelo to PV, but I only took it the first day to get my gear to the shop. The other days I took the collectivo [local shuttle] for 20 pesos. Take Barcelo's shuttle or walk to the front entrance and catch the colectivo there. They run every 5 to 10 minutes. Another 5 minutes to PV + a nice 5 to 10 min walk to the marina. The folks at Aquanauts will take you back the first time and show where to get on and off the shuttle.
I dove a week+ and ~ 75% of the customers were repeat biz and the other 25% were referals - says alot for the service and experience. They are bottom time oriented and you dive your computer/skills. They are very accomodating and safety oriented. The reefs are only 5 to 15min away, so this is easy diving. July water temp was 84F /rash guard; no wet suit. 6 to 8 divers max. We grouped up by skill and desire. Sometimes the entire boat dove the same location. Sometimes we dropped off at three different spots - like I said customer oriented. You will not get this at the resort. The resorts group new divers and experienced divers together with the least common denominator setting the bottom time. I let Aquanauts know i wanted a night dive and they set it up. They also had a number of advanced skills courses in progress, optimized to people's schedules and skills. If you have the buoyancy control, I recommend doing a cenotes dive at the end. Awesome experience and a great fresh water rinse of your gear. Avoid the resort cenote guides - we met two of them at one cenote and it was a cluster-F. We got in ahead of them and took our time. Had a short surface interval and was about to start our second dive when they were returning with another group. That meant they dove two caverns and transitted back and forth to the hotels in the same time we dove one cavern and had 30 minute SI. They could not have spent more than 15 to 20 min in the water. Search the scubaboards/google and you will see nothing but praise for Nick and Mauricio as divers and instructors. I was so happy withthe experience I left a oustanding review for them on TripAdvisor. I also attached some cenote photos. Even with my poor photo skills, the awesomeness can be seen in the pictures.
If you go with them, say hi from Cliff