Need Help Planning a Day in Montego Bay

My fiance and I booked cruise tickets on the Carnival Freedom on a whim to celebrate our 5 year anniversary, and are now looking for suggestions and recommendations as to what to do or what excursions are best. My fiance and I are both 26 and are adventurous people, so ziplining and other more intense activities are welcome!

Reliable companies and tips on transportation are much appreciated!

Following this because we will be there in December and there doesn't seem to be a lot of info out there.