princessmelody,
The excursion you are refering to is a canopy tour or "zip lining". Not sure which island you will be visiting that does the canopy tour. I know they offer them in Costa Rica, Belize and Jamaica in the Caribbean. Anyway, I wrote a special report on my "zip lining" experience in Costa Rica that you might find of interest:
http://www.caribbeanportreviews.com/PuertoLimon8.htm
Nancy