Cozumel is designed for all skill levels for diving. Your dive op will customize your dives to your experience level. The certifications are really not necessary. Drift diving is awesome, just relax and make like superman. It is easy to get separated from your buddy though so keep and eye on that. By all means, do a night dive. You will thank me later. It is just like diving for the first time all over again. Aldora and Blue XTSea are huge supporters of this forum. I will be diving with Aldora in November because of their support. blue XTSea did not have any morning times available so maybe January for them. I love Blue Magic and their sleep and dive packages are very reasonable...had it not been for Aldora and Blue Xtsea's support of this site, I would be going with them again. dive With Martin is great as well and provides the same level of service as the rest....which is top notch. DWM may be the oldest op on the island for good reason. Certifications are good, but absolutely not necessary for Cozumel diving. Your DM will take care of you if you have any issues. Between dives, you can discuss anything necessary during the surface interval, and you WILL leave a better diver, no instructor necessary. Some call Cozumel Diving "babysitting diving" and to some extent that is true. dive plans are basically limited to depth maximums and dive so you surface with 500psi. If you run low, most will let you surface and your buddy takes the DM for the rest of the dive. My daughters and wife went on their first dive after ow cert in Coz, no problems and the DM took care of them like they were his own. Main rule would be stay away from the cattle boats, go with an op that uses 6-pack boats, and each will do something a little different. Aldora dives steel 120's so you will get longer bottom times, especially if your an air hog like me. Most will valet your gear if you bring your own. Surface intervals will range from boat, beach, or club. Pick up point will vary as well. Bottom line, you're going to have a great time, certs or not. After the back roll, prepare to be amazed. Relax and have fun!! Please post your review when you get back and don't forget to do a night dive!! Jay