We were on the Jewel in January. What a gorgeous ship!
At Cartagena we took an excursion that we booked on the ship called "Deluxe Cartagena & Fortress". Friends of ours who had been on the same excursion highly recommended it and I would highly recommend it to you. We experienced so many different features of Cartagena and our tour guide was excellent.
Enjoy your cruise and welcome to cruise-chat!