Underwater caves of Yucatan

When you hear Mexico, what comes to your mind might be the Mayan ruins that have a lot of historical value. But more than that, it turns out that Mexico also has the longest underwater cave in the world: Sac Actun. Located in Tulum Village, Quintana Roo, Mexico, this giant cave was discovered in January 2018. Specifically, when a team of divers who are members of the Gran Acuifero Maya (GAM) project – which is dedicated to the study and preservation of underwater waters in the Yucatan peninsula – managed to find the cave, after exploring a maze of underwater canals for months.

The cave search project itself has been started since March 2017 with work carried out by GAM exploration director Robert Schmittner and a team of specialist cave divers. The search team has even conducted research for approximately 14 years, to make a mapping of the shape of the labyrinth and alleys in the cave. Previously, researchers concluded that the underwater cave stretched to about 262 km. However, upon further investigation, the Sac Actun underwater cave is still connected to the Dos Ojos underwater cave system. The discovery also revealed that the two underwater caverns were connected in a complex maze of 347 km long. That fact makes Sac Actun considered the longest in the world. Before this, the underwater cave system Ox Bel Ha with a length of 269 km which is located in the south Tulum, Mexico, is considered the longest. System Sac Actun, is located in the northeast Tulum, is in second place, with a length of about 262 km. The third order is occupied by the Underwater System Koal Baal, with a length of 92 km, and in fourth place with a length of 84 km, is occupied by the Underwater cave system Dos Ojos.

Now, thanks to the painstaking exploration of the massive underwater cave system, the top position is bestowed on the Sac Actun System. According to the rules regarding caves, when two cave systems are connected, the largest cave absorbs the smaller cave, so the name of the small cave is lost. The next goal is to connect Sac Actun with three other underwater cave systems, which are remarkably close to each other and are located in the municipality of Tulum.

According to data from Quintana Roo Speleological Survey, there are 358 giant underwater cave systems in the north of the state, representing nearly 1,400 km of clean waterways. From the same research, the GAM exploration group also listed another important system, 18 km long, which has hitherto been dubbed the “mother of all cenotes”. Literally, cenote comes from the word dzonot or ts’onot which in the Mayan language means “holy”. For the Mayans who have inhabited the Yucatan Peninsula for generations, the existence of cenotes is considered important in life. Cenotes become the foundation of residents as a source of water in areas with a long dry season and without the availability of water on the ground surface. This is the reason why all Mayan villages were built around cenotes. From a spiritual point of view, cenotes also have an important meaning. Throughout the region, the Maya were known to regard some cenotes as having a particular religious significance. It is believed, the cenote is a kind of door leading to another world as well as a place to communicate with the gods. Findings through archaeological research themselves have shown that there are indeed religious rituals that occur around the cenote, one of which is the ritual of human sacrifice.

It is estimated that there are about 7000 cenotes spread across the Yucatan Peninsula. Of the many cenotes, most are protected sites that are small and not always open so that the water surface can be seen clearly from the outside. The formation process of cenotes takes over millions of years. The bedrock here consists of thick limestone that allows erosion to occur more easily, especially when the water is acidic. This calcareous platform was formed 66 million years ago when life in the shallows died out and petrified. Eventually, the limestone platform begins to be eroded by slightly acidic precipitation, which eats up the underlying rock, forming caverns in the water. The sea level eventually dropped, causing part of the limestone roof to collapse, creating a cenote. The sea level then finally rose again, and the caves were flooded.

The researchers hope that in addition to highlighting the geography of Mexico’s underwater waters, this discovery would help understand cultural developments in the region, which was rich and dominated by the Maya civilization before the Spanish conquest. This gigantic cave holds a treasure trove of Mayan secrets. It is the most important buried archaeological site in the world, as it has more than a hundred archaeological contexts associated with the Mayan civilization which has probably never been found anywhere else on Earth, among them are evidence of America’s first settlers. On the subaquatic tunnel floor of Sac Actun, divers also found artifacts from the Mayan civilization, including ceramics, Pleistocene megafauna, and even human remains. In addition, the discovery of this ancient artifact also reveals an even more ancient prehistoric story. In a study, scientists report that they have discovered the largest mine in America dating back 12,000 years. Inside the cave, the team found a variety of evidence of ancient mining activity, including excavation tools, ochre extraction, navigational markers, and ancient fireplaces. However, according to the researchers, the discovered cave may be much older, given that there is evidence of skeletons dating back 12,800 years. For some reason, miners at this site stopped extracting ochre about 10,000 years ago.

Part of GAM’s mission is to understand the history of the region’s ancient Maya civilization and its relationship to the aquifer system. Finding the connection of these underwater caves required hundreds of hours of treacherous diving and mapping in the submerged labyrinth. Although the Sac Actun underwater cave has been found, researchers will continue the exploration. They will study the water quality, the biodiversity that depends on it, as well as to protect and conserve this extraordinary geological feature as a valuable natural resource.