My blatant cheerleading plug - Bottom Time Divers - single owner/DM and patient. Larger operations may have their hands full with more divers but you never know. It depends on the DMs and how they run things. If I were in their shoes, it would try a smaller op to get personalized attention or as mentioned, get a private DM.
There are plenty of qualified dive ops in Cozumel. I suggest contacting them with specific requirements and booking before getting on the cruise and not waste valuable time upon arrival. They should make sure to mention this to whichever dive op they use.
Also they should be careful of going outside the cruise line. If thru the cruise line, and the dive ops is late then I have heard the ship waits. If not and your friends are late coming back regardless of fault, the proverbial ship sails without them. If outside the cruise line, make sure to get the schedules set and have a bit extra time for contingencies.
There are plenty of qualified dive ops in Cozumel. I suggest contacting them with specific requirements and booking before getting on the cruise and not waste valuable time upon arrival. They should make sure to mention this to whichever dive op they use.
Also they should be careful of going outside the cruise line. If thru the cruise line, and the dive ops is late then I have heard the ship waits. If not and your friends are late coming back regardless of fault, the proverbial ship sails without them. If outside the cruise line, make sure to get the schedules set and have a bit extra time for contingencies.