Cave Cartography

Project Xulo

I have always wanted to map a cave. Back in 2014 on a long trip to Mexico I did a survey and cartography course with Alex Reato. The idea was to start a mapping project straight after the course, but due to a stubborn ear infection I ran low on time and had to abandon the idea.

Now many years later, after the move to Mexico, I finally have the opportunity. Survey and especially cartography is a very time consuming activity. It not only demands several dives and multiple hours underwater, but also many hours entering the data afterwards. It is also not something where you get a quick result, you have to commit to the process. Due to the nature of the project it is not easy finding commited dive partners that are willing to invest their time. But I was lucky to have found a partner for the project in Shannon, a local cave diving instructor.

The idea of mapping a cave together was born over some beers, but we didn't have a location yet. So we started checking out some sites and asking local experienced cartographers for advice.

We ended with a Cenote named Xulo. The reason we chose Xulo is a combination of size, and popularity. First off, it is not so big. Since it is our first cartography project, we don't want to start with taking on a monster.

Second, it is a relatively popular cave without an existing map. Therefore a map would be helpful to the visiting divers and an asset to the dive community.

the entrance of Xulo

A little bit About Xulo

The cenote Xulo is located close to the town of Muyil about 20 min south of Tulum. It is named after the owner, but it is also known as UKU CUZAM, meaning cave of the swallows.

Xulo is part of the Catapillar system which is approximately 33 km long. For our map we stick to Xulo itself which is around 3,5 km long.

The cave was first explored by Alvaro Roldan back in 2013. He was also the one who discovered the connection to Catapillar. Other main explorers are; Kim Davidsson, Mauro Bourdignon, Philip Lehmann and Skanda Coffield.

To find the entrace you will have to walk down the stairs into a small dry cave, where you will find a pool of water from where the mainline starts. The cave itself is a sidemount cave. While the main tunnel has some big decorated rooms and is big enough for backmount, all the side passages are small to very small, and is definitely sidemount territory.

plenty of tight restrictions off the mainline

Survey

The first step of our project is a resurvey. You survey the cave by measuring the lenght of the guideline in between tie offs (also called stations), the depth of the station and the azimut of the guideline.

We measure all this with a device called the Mnemo. While swimming with the device clipped onto the line it not only measures the length, but also depth and Azimut.

While one diver handles the Mnemo the other diver takes notes. These notes include information that will be added to the survey data to further describe features of the cave, such as restrictions, intersections, possible leads, etc.

After the dive the data is entered in a program called Ariane's line.

The data will form a ''stick map''. Each line represents a tunnel. The different colors are to make a distinction between the main tunnel and the side passages.

Still a work in progress

To give you an idea of the time consumed:

We are almost finished with the Xulo section of the system we want to include in our map and we have surveyed a total of 3,5 km of cave.

This took us 9 dives averaging 4 hours per dive. A total approximate time spent underwater of 36 hours.

On top of that there is some time spend on the laptop entering the data. And by entering data, I mean swearing at the computer and constantly messaging Sebastian (thank you Seb!).

It has been a great learning experience as well. Besides getting more accustomed with using the Mnemo and the software, we are also getting more efficient in note taking, polishing communication and getting more strategic in dividing our tasks underwater.

The days are long and gruelling in the summer heat, but all in all we are having a blast!!

The next step, the actual cartography, has to wait until I return from my trip to Europe. We have some cool unorthodox idea's to include in the map, and I can't wait to continue and start drawing. Keep an eye out for part 2 of this blog later this year

Shannon surveying the deep section of Xulo