I made a last minute reservation on the AOS (RCCL) so booked my dive in Cozumel with the ship. BIG mistake. RCCL uses Sand Dollar. Nothing against Sand Dollar but they took us to 2 sites .. site one was an average dive so I'll say a "C" on it but dive 2 was right outside the little marina and was an "F". Waste of money. Also, NO walls .... they claim there were too many novices on board. Again, I know it was my mistake but be aware when booking thru the ship !!!