Date of Exploration: March 3,2011
This cistern is located in a large courtyard in the middle of the cathedral museum building. The cistern has a long passageway which opens up to a large circular room (also located beneath the courtyard). There is a second passageway that comes off of the circular room but the floor sloped up quickly, making it impossible for the ROV to explore further.
Shown below is the sonar image illustrating the shape of the cistern.
California Polytechnic State University
Marine Resources Development Foundation