On your computer, open Dive Buddy, go up to the right and click on Scuba Earth, enter Cartagena and you’ll find no one has entered anything :( When you get back please fix that situation !
I once had a Columbian girlfriend, I thought she would teach me more Spanish but what she taught me was why Hispanic men needed 3 jobs. She said she was going to take me meet her family, translated that meant she wanted me to pay for the trip including her side trips while I was diving :(
Online I found a lot of dive shops that promised good diving but little on individual sites. In most cases the DM chooses the sites anyhow and the first is always some poor site where he evaluates your skills before turning you loose on his favorites.
Up under Dive Sites there are 3 pages of dive sites in Columbia but just not near Cartagena