National Geographic
Menu

Colonial Shipwrecks of Colombia: Diving Anomalies

Juan Martin searches for the anomaly with a metal detector while Fritz Hanselmann runs the search line. Credit: Chris Horrell/The Meadows Center for Water and the Environment at Texas State University
Juan Martin searches for the anomaly with a metal detector while Fritz Hanselmann runs the search line.
Credit: Chris Horrell/The Meadows Center for Water and the Environment at Texas State University

National Geographic Grantee and Texas State University Research Faculty Frederick “Fritz” Hanselmann and a top-notch team of archaeologists from Colombia and the United States are leading an expedition to locate and document historic shipwrecks off of the Caribbean coast of Colombia.  Follow along with Fritz’s updates from the field. 

Once an area of the survey grid has been thoroughly covered with the magnetometer, diver survey is required in order to ground truth, or search for what gives off the signature recorded by the magnetometer.  While Bert and Andres continued the mag survey in other sections of the area, Chris, Juan, and I began diving the anomalies that were mapped on our GPS.  First, we position ourselves as close as possible to the waypoint on the GPS, then we drop a weighted buoy to the seafloor, which is used as a base for the visual survey.  Second, we attach a line to the buoy and which is used as the base to conduct a circle search in the general area of where the anomaly is located.  Third, divers are spaced along the line depending on the visibility.  This means that the better the visibility, the farther apart the divers can be spaced, but always within sight of one another.

Juan Martin searching for an anomaly with a metal detector. Credit: Fritz Hanselmann/The Meadows Center for Water and the Environment at Texas State University
Juan Martin searching for an anomaly with a metal detector.
Credit: Fritz Hanselmann/The Meadows Center for Water and the Environment at Texas State University

In our case, we had a search team of three, to look for any metallic objects that might have created the anomaly. Once we are all set, we begin a circle search.  I ran the line while Juan and Chris alternated using the metal detector.  Once the initial circle is completed, the search can be expanded from that point in a wider circle.  Typically, two circle searches is usually the norm and these dives don’t last much longer than 10-20 minutes, depending on the accuracy of the buoy drop and the conditions underwater.  We were lucky for the most part and had favorable conditions.  Given that short duration of this leg of the overall project, we were only able to spend a day and a half diving anomalies.  The results on the anomaly dives vary, as modern debris and geologic features can also be the causes of an anomaly.  In this case we found a number of geologic features, older but modern concreted machetes, and some fishing tackle.  Even though we didn’t find anything historic, we leave Bahía de Gloria with a strong desire to return for more work.  At the end of the day, it has to be said that we had a lot of fun and that’s one of the reasons a lot of us become archaeologists…we’ve never really grown up because we never stop having fun!

Funding and support provided by a National Geographic Society-Waitt Grant, the Universidad del Norte, the Ministerio de Culturathe Instituto Colombiano de Antropología e HistoriaHalcyon Dive Systems, Cabañas Anayansi, Dive and Green Dive Center, the Way Family Foundation, and The Meadows Center for Water and the Environment at Texas State University.