Blue;
I stayed at Iberostar and dived with Dressel this past Oct. I have dived with them for the past 7 or 8 years. They are an outfit with their main office in Spain. In fact if you book with them and pay ahead of time you can get a 20% discount. They will allow you to carry your unused dives for up to 3-5 years. When making your reservation mention to them that you have not dived in salt water. They have a pool-check option but that doesn't help you much since it is not salt water. They operate big boats and have maximum of 8 divers to a dive master. They may carry as many as 3-4 groups in one boat. In my last trip they had 4 boats running with each boat carrying 16-24 divers. It can get a little hectic. They will give you your weight on the boat so ask the dive master for suggestion and the dive master always carries extra weight should you need it while under. The dive master will pair you up with someone but since he/she doesn't know your skill level the first couple of dives would be more to gauge your skill. Be sure to tell the dive master your skill level and discuss anything of concern, such as swim thru, descend concerns and so on. Cozumel is drift diving so be sure to listen to the dive master's planning as they will sometime give you tips on drift diving and staying with the group. Batista and Maddy are the shop managers and they are very helpful. Manuel, Julian and Scott are some of the dive masters who will help you too. Captain Miguel and mate Francisco are also very nice and helpful. There is a small area for storing your equipment, but be sure to bring your own lock. If you call/Email the main office in Spain ask for Marjon and tell her Mo sent you.
Have fun and enjoy your dives.