I've visited Cuba twice, in 1995 and 1996. The first trip was a regular scuba diving holiday, the second was as guests of the Cuban Government!
Our first trip was to Cienfuegos on the South coast of the main island for one week, with a second week on the Isle of Youth. Our first week went well, although diving was delayed by the remains of a tropical storm, but we played every game you can think of in the pool, and learnt to dance in the hotel! When we eventually did get some diving in, it was good, but somewhat murky. We were, therefore, looking forward to our week on the Isle of Youth, where the diving was reputed to be "World Class". But, it was not to be. We arrived after a long day travelling to discover (eventually) that the hotel was fully booked and we were not on the guest list! It actually took us 5 hours at the airport to work this out, by which time the last commercial flight back to the mainland had departed - which meant, with the non-working telephone system, we were somewhat isolated. I'm still not quite sure how, but we resolved this by renting a plane and crew from the Cuban Navy to fly us back to Havana, where a nice man with a big gun found as some taxis who found us a less than desirable hotel, after a manic ride through the streets of Havana at 1.00am. At speeds up to 70mph, this was somewhat like a computer game, where you can't hit the pedestrians/cyclists/children etc!
Anyway, the problem was sort of resolved by finding us another hotel on the South Coast, 2 miles from where we'd spent the previous week! We dived, and hired jeeps to look around Trinidad - a beautiful little town of old Spanish Colonial architecture, gently decaying.
On
our last day, we were invited to Havanatur's Head Office (one of two State
tourist companies), where Julio Santos, the Commercial Director for Europe and
Asia offered us our free return trip as compensation. This was followed by a
superb lunch at El Fioritos, and a tour of Havana - the old parts of the City
are well worth seeing.
So,
in 1996 we returned. We made it to the El Colony Hotel on the Isle of Youth, a
very relaxed place, and enjoyed over one weeks worth of excellent diving. All
the diving is about 50 minutes fast boat trip from the hotel, with lunch at a
small restaurant near the dive sites. We quickly developed a routine whereby
the boat crew would buy fresh lobster from the local fishermen and cook it to
perfection while we were diving in the afternoon - so our return boat trip was
completed with excellent lobster - not all Cuban food is good, but the majority
is acceptable and some, like this, is superb.
Cuban
diving is not big on large fish populations - there are fish, but the waters
don't teem with them as they do in the Red Sea or the Maldives. It is big on
superb sponges and corals, though - including black coral, which looks something
like a brown weed! We did see some huge rays, lobster, and all the usual reef
fish.

Our final week was spent at Club Varadero, one of the "all-inclusive" resorts on the Varadero peninsula. The diving here, on the Atlantic coast, did not provide good visibility, so we hired some jeeps and went to find the real Cuba. It's a great place - all those big, old American cars, old technology blended with very new technology - something of a time warp. We did get lost at one point, and found that the latest GPS system is nowhere near as efficient as directions from two local boys in exchange for a Dollar and some soap!
So, don't let the above "horror" story put you off - Cuba is a great place to visit - although I guess if you are American, you're not allowed to go and find out, are you?