I won't detail my Cozumel experience here right now, other than to say that Emerald Dolphin Dive Services was the WORST dive operator I've ever experienced, and I wouldn't wish them on my worst enemy ! The boat was fine, the tanks were full and the Nitrox mixes were correct/appropriate, the DM/crew operated safely.. (to the point of paranoia) ......but the DM severely restricted our dive times ( 700 psi/45 min 'rules') and I've never been with an operator so obcessed/fanatical about terminating dives early....moreover, he did guided tours over the 'best' of Cozumel's desert wastelands, on dive # 5, as we decended to 70 ft to begin what might have been a half-way promising wall dive, he deliberately immediately pulled us off the wall, swam us head first into a current while swimming 180 degrees away from the wall, we spent the next 40 min skimming the bottom at 50 ft. deep staring as an endless underwater sandy plain until he ran us out of air......... downright criminal ! (this was the dive where I threw in the towel and was ready to return home immediately !