Just found more info. on the horseback riding you can go to
www.chukkacove.com for details on booking off-ship.
or here is what Carnival's web site said:
"Enjoy a 20-minute ride by air -conditioned coach along the coast to Chukka Cove. After a short orientation you will be matched with a horse suited to your ability before departing on a ride to the beach in the care of 8-10 guides who unsaddle the horses while riders change into their bathing suits. Ride your horse bareback into the ocean for an experience of a lifetime! You will be served non-alcoholic drinks on the beach before returning to the farm where the bus awaits. Note: Jeans and solid closed toe shoes highly recommended. Wear bathing suits beneath you clothing Approximately 3 ½ hours "