Treasure Beach is way off the beaten path but it is worth a look as it is pretty rustic and not as heavily touristed as the other beach towns. But boy, do they make you pay for the privilege of "isolation," rooms at the popular Jake's Place start at 150usd a night.
Yet we saw a quieter side of Jamaica here. It was fun to see local people singing gospel in churches and women in their Sunday best, just doing their own thing. Transport can be arranged for about 80 USD. We drove here but it was not an easy journey.