My son and I had the pleasure of doing a cenote dive (Dos Ojos) and an ocean dive with Dressel Divers in Play del Carmen this Christmas. They are the on-site operator at the Iberostar Quetsel in Ply del Carmen and Barcelo Resort south of there. I didn't expect the high level of personal attention from their divemasters - who even accommodated many languages. Highly safety conscious! Net, Ana and Lara are all excellent.
This was our first experience diving in this area - didn't have time for a Cozumel excursion, however. I have read other reports on Dressel's operations which were so-so. But this was a great experience and I can recommend them at these resorts.