Ok kids here is the scoop!!!
I went to the Excursions desk when I got onboard and the the zipline was indeed soldout. The few tickets they had left were sold. :evil:
The zipline in St. Maarten were also soldout.
She put me on a waiting list. Now the only chance I had was to wait and see if anyone cancelled this excursion.
On the day of the excursion I got a call in my cabin at 7:30am to tell me someone had cancelled and there is room for me. However the tour meets at 8am.
It was too late at that point so I told the lady on the phone I would not go.
Lesson that I have learned here is to book excursions asap and don't wait until the last minute.
I guess I now have an excuse to go back to San Juan becuase I really want to do that zipline.