Hi Barry.
If you book with a diveshop in Varadero and the bus is going to pick you up in the morning, make sure it is the right bus. I booked with Gavioti and got picked up by Barracuda. I never realized the mistake until after the bus stopped at 6 other resorts getting divers and finally arrived at the Barricuda Dive Centre. Complete with 5 couples who had paid deposits with Gavioti. I think they do this alot. We were told not to worry about it, they would sort it out but we should just go with them. When it was over we had to pay the full price to Barracuda, plus lost our deposit with Gavioti. We also had uncertified divers, just the pool course at the resort, and the dive master took the group to 28m. Left the newbies alone at 10m. The whole thing was very unprofessional. I doubt I will ever go back. I hope you have a better time than we did, just be careful. I thought the bus ride across island was interesting, and the Bay of Pigs was nice. It seemed like a long drive for not much time in the water though. They used DIN. Anyways, good luck.
Troy