By Brittany Callan
Medill Reports 

Rio Secreto, Yucatan Peninsula – The first thing that struck me was the darkness.  The feeble light from our helmets struggled to illuminate the cave around us.  You could either walk with your light pointing at the ground or use it to look around the cave.  Not both.  That was a challenge –  this was my first time in a cave and I wanted to see everything.

Where we start walking, the cave’s natural decorations of dramatic stalactites and stalagmites look ancient and fossilized.  These are the older formations. Geologist Patricia Beddows explained that she looks for younger stalagmites to monitor drips, but either can be sampled as a paleoclimate record.  All of the formations come from water moving through the calcified rock and soil, sometimes aided by tree roots.

As we walked further off of the tourist trail, we could see the difference between old and new.  The stalactites and stalagmites that are younger look more yellow, with a texture resembling  candlewax after a candle has been burning for awhile.  This  was the room in which Beddows did her research and affectionately called “the lab.”

We also walk past a table and chairs where the highest paying tourists get to drink wine and enjoy food in a kind of cool and mysterious cave cafe. Beddows and our guide Fernanda Lases Hernandez ponder whether having a few higher paying tours rather than multiple cheaper ones can help reduce the impact of tourism on the cave system.

We were walking into the depths of Rio Secreto so that Beddows, a professor and researcher at Northwestern University, could check on her fleet of sensors that were busy collecting data on the number and frequency of drips of water hitting them from the stalactites above.  Each time a drip hit  the plastic drum of the data logger, a green light flashed.  Beddows is studying the groundwater recharge in the cave system, the process in which water moves from the surface  above into the cave. Recharge is a term for replenishing freshwater supplies. Working in Rio Secreto lets Beddows gather an entire population of drips.

Beddows checked to make sure all of her data loggers were working and pulled some that weren’t.  As we were walking on the way out, she stopped Lases and told me and my colleague, journalism student Tiffany Chen, how to guide ourselves out of the cave.  I looked for the red guide strings that led to the exit and tried to walk in between them to find the way out.  At times, it was difficult to find the strings and the path seemed mostly unfamiliar.  It felt easy to get lost here.

Two days later, Chen and I came back to the cave to see it from a tourist’s perspective.  Ecotourism is wildly popular in the Yucatan Peninsula.  Rio Secreto is only partially commercialized for tourism, though.  Lases estimates that 10 percent is used for guided tours, and the guides switch routes to try to contain the direct impact.  The rest of the cave system is sequestered for research and conservation. The total  length of the Rio Secreto cave system is 38 kilometers (about 23 miles) and the total area of the cave we experienced is only a few hundred meters.

Lases and guide Raul Padilla Borja stopped before the tour to talk to us about the importance of conserving the cave ecosystem.  They warned us about keeping our heads down to prevent  breaking any of the stalactites.  Later, when we were in the water,  Padilla rubbed his hand on the side of his nose and then put it in the water to show us how the calcite in the cave rafts. It looks  like ice and disperses immediately.

“It is very important to inform our visitors, people that are coming as our guests to Rio Secreto, about the fragility, the importance, and the uniqueness of the aquifer of Rio Secreto,” Lases said.

Rio Secreto, like many other places in the Yucatan Peninsula, is in a struggle  to conserve the purity of  the groundwater.  I talked to a dry cave explorer, Peter Sprouse, about how he thought the cave operators were doing.

“They have made pretty significant efforts in conserving the watershed that leads to the caves. They have to fight off some developments from Playa del Carmen to the north.  It’s a constant battle to them, to keep the water clean,” Sprouse said. There is a threat of seepage of wastewater as the development accelerates.

But for now, the ecosystem seems to be doing well.  On our tour, we were lucky enough to see two blind fish – white fish that have empty eye sockets because they have evolved to live without eyesight since it isn’t useful in the cave.

“This fish is in the red list [of threatened species] and they are also very fragile to pollution. But, at the same time they are an indicator that everything is going well.  The presence of a blind fish means the ecosystem is in very good shape,” said Padilla.