OP!
Do Not go to Dunns river falls, i garuntee your cruise will have an excursion there. Its really fucking gay.
Stay away from Montego bay, its touresty as fuck
Like everyone said, if your into partying. hit up the bar, smoke wee, lay on beach. Like someone else said above the weed usually isnt that good, but the blow is.
Also Negril is a cool town, im not sure where your going to be but Bob marleys grave is there.
Ive stayed in Jamaica 4 times and i loved it everytime. Like anywhere else, there are great people there, but there are a shitload of sketchy ones. Dont trust anyone,