We had planned a cruise in December to go dive in Cozumel, but changed our minds and just went and spent a week there. But here is my Cozumel experience:
We dove with Scuba With Alison, and there were cruisers on her boat every day; she adjusts her departure schedule around them, and she has never gotten someone back late. I'm not sure about the 11 year old, since that is a non-standard cert, isn't it? Just make sure in your email to her (google the name, her website will come up) you explain what you are looking for- and she can tell you if she can accommodate it.
We used her rental gear, and it was excellent quality- and tasted like fresh detergent every morning
Included a computer, though we chose to bring our own. We brought our own fins and masks as well, but others rented those. She rents only shorties, but the water is warm and some people dive without a wetsuit at all.
Every single dive site was amazing. The dives you do will be somewhat dependent on who is on the boat and their experience level. Day 1 we dove 60 ft and 30 ft, because I was a nervous wreck, so she planned an easy day- when booking she told me that if I wanted to spend all week above 60, she could make it happen, but I got more comfortable and went down to about 80. All the other days we did around 80 ft and then a slightly shallower dive. Every single site we went to was amazing- we went to 11 different places. The reefs are incredible, and there was a good variety of fish life. The visibility is phenomenal.
Alison is also very safety conscious- for brand new divers, she will signal often to ask about their air. For some, she would actually go look at their gauges for them.
Her boat is excellent, double motors, very fast, very comfortable. She takes out groups smaller than 8 people. You can roll or giant stride off the boat.
Diving with Alison, you dive your own tank, not a pre-timed dive. When someone runs low on air, she shoots an SMB and goes to the safety stop with them, and then sends them up. Their buddy can go up with them (I chose to stay with my husband) or rebuddy with someone else in the group and extend their time. Her Captain is excellent, and we never waited more than 2 minutes in the water to get picked up. That "long" wait, she actually popped her head out of water to yell at him, since he was taking so "long". We saw other people bobbing along for 5-10 minutes waiting for their boats, so I appreciated the quick pick ups.
Other ops I've heard good things about, but have no experience: Aldora, BlueXTSea, Dive with Martin, Sea Robin, Tres Pelicanos.
