I went to Cuba in 2001 for 10 days but was not diving. I had started diving before then but this was a vacation trip from UK via Texas and was more focused on sunshine, Cervezas and Mojitos.
It was the same idea and I wanted to see Cuba before Castro (#1) died and the country changed forever.
I had heard that the diving is good and there are several chambers available if necessary.
What we encountered in Havana and the west end of the island was really limited/restricted resources such as expensive fuel and broken water pipes, overloaded public buses and all sorts of problems for the locals. However, it was gearing-up for tourists (non-US) with plenty of Europeans and a rising number of restaurants, hotels and bars particularly in Havana, Old Havana and the surrounds. This runs out quickly in the countryside and once there I realized that it would be more difficult to travel to the poorer east end of the island.
I'm sure it was quite possible then but we settled into partying rather than roughing it across country. I'm sure it is a lot easier now.

iratewithhat2:
I had considered getting a tourist flight (an old bi-plane) to one of the islands on the south side which may be an old pirate haunt. After deciding against it, the news a few days later described one of these planes breaking up and falling out of the sky likely due to poor maintenance and lack of legitimate spares. Good (or lucky) call.
It was difficult to arrange the travel to Cuba and it cannot be done online since most travel sites take you on to US servers and this is blocked. We booked it all using a UK travel agent and flew via Jamaica since there are no direct flights via US. It is possible to ask that Cuba does not stamp your passport. Now that I have US residency, I would be careful to check the laws that apply and adhere to the relevant restrictions and clauses.

iratewithhat:
cheers,
McLot