We booked the Carnival Ecstasy 5 day sailing from Mobile, AL with stops in Costa Maya and Cancun. We could not pass up the low price. 1479 passengers about 73% capacity. There were no lines for anything. There were ALWAYS lounge chairs available except for directly next to the pool.
Although this is an older ship that is scheduled to be retired (scrapped) in the fall, it was well worth it to take this cruise.
The port area at Costa Maya is small with narrow walkways. Crowded and not enjoyable. Lots of hassle from shop workers
Carnival docks at Puerta Maya. This is a different location that NCL and Royal Caribbean. The port area has shops and nice wide open walkways. Not crowded. Not hassled by shop owners. Lots of shopping and break break type excursions. Note: Cozumel is almost always very windy and the shorelines are rocky. Bring beach shoes if you plan to go to the beach.