Fonfon5,
Do you have to go to Montego Bay?
I've traveled to Jamaica many times
(I had a family member that married a Jamaican Girl)
Jamaica is a lovely country but its economics make it a pretty poor dive location. People eat most every thing they can scoop up out of the water and you can't blame them. You will also be harassed at every turn to buy anything from trinkets to any sort of drugs imaginable. After a couple of trips you kind of develop a look that keeps the locals at bay but if it is your first trip or two, expect to be overwhelmed. Jamaica is the only place in the Caribbean where I strongly recommend being at an all inclusive resort locked away from the local populace. (I've got some friends that would disagree but they also have a good deal of experience in the country and they vacation at a private villa many miles from any tourist venue). Montego Bay is the tourist hub of the country and the area is particularly polluted. Really watch yourself at night, stay at home or at least on the main streets. The last time I was in the the area was six years ago, and the algae was particularly bad on the shallow sites I visted. To me a vaciation in Jamaica is just that, a vacation. It is not a dive vacation.
If you are stuck going to Jamaica, I would recommend trying to get away from the Montego bay area and going to Ocho Rios. There are a couple of pinnacles there that were not in too bad a shape the last time I was there. I'd recommend it over Negril for diving.
I don't want to run down the country too much, as I have aways enjoyed myself there and I usually try to at least fly though the Mongego Bay Airport once a year to stock up on Rum and Coffee. The place is simply not a good dive location. Even if there was no over fishing or nutrient rich (sewage) runoff from all the coastal resorts, it is a rain forest dominated island and has a considerable amount of fresh water runoff into the sea. Jamaica's smaller and dryer neighbors offer much superior diving.
Here are a few words on Sandals resorts in Jamaica (remember I have not been close to one of these for over six years and my info may be dated).
Sandals was one the first chains to do the all inclusive thing, and their chain was started in Jamaica. The Sandals resorts in Jamaica are all fairly old as far as island resorts are concerned and do not have as many amenities as their newer ones in the Bahamas or St Lucia, or of their other competition on Jamaica. The resort in Montego bay was their first and is really very simple.
If you are stuck with going to Jamaica I'd at least try to book another resort.
There are many others and most all of them will have better facilities and service.
Remember none of the all inclusives will have a very good dive operation. They all will be set up for the lowest common denominator (which is not very high) and will simply want to put you in the water twice a day at the most convenient site and get you back out of the water ASAP so they can get paid and continue to screw off.
If this is where you are bound, have a great time. Drink the rum and coffee, play some golf, and enjoy yourself. Just don't expect very good diving or snorkeling.
I'll be glad to give you more input if you'd like.
Clyderyde