Hello! We are looking forward to a Carnival Cruise on June 20, 2010 to Cozumel, Jamaica and Caymen Island. We have excursions in mind for Cozumel (Paradise Beach) and Caymen Island (the turtle farm) but we are having a hard time deciding what to do in Jamaica. My 12 yr old daughter would like to zip line.

I had my eye on the tubbing down the river trip, but I am not sure if I can take my 8 yr old son who is not a strong swimmer, but does fine with a life jacket.
I have seen some posts on other sites that warn against booking outside of the cruise line.
On the Carnival website all of the Jamaican excursions must be booked onboard - so at this time I can't even see prices. We will be docking at Mantego Bay therefore Dunn falls will be too long of a trip with two kids.
Any suggestions would be greatly appreciated!