Underwater archaeologists made a stunning breakthrough in their investigation of eastern Mexico’s submerged cave systems in early January 2018. The divers were part of the Gran Acuifero Maya, an international research initiative, and they had a very special assignment. The scientists’ recent five-year mission has involved the exciting adventure of exploring directly underneath the Yucatán Peninsula. And the team’s latest discovery has linked two underwater cavern complexes, making their find the largest submerged cave on Earth.
The underwater marvel lies beneath the Caribbean coast of the Yucatán headland, near the popular tourist destination of Tulum, in the eastern Mexican state of Quintana Roo. The two cavernous systems that have now been linked are Sac Actun and Dos Ojos. The former has therefore effectively subsumed the latter, and together the two underground complexes comprise about 216 miles of flooded tunnels. The lengths of these channels are also regularly punctuated by some 248 sinkholes, which are known as cenotes in American-Spanish.
The Gran Acuifero Maya project has, then, gathered together a team of scientists from different disciplines to explore and map the caves beneath the Yucatán Peninsula. Its members include researchers from Washington, D.C.’s, National Geographic Society and Mexican educational institutions the Aspen Institute Mexico and the Technological University of the Riviera Maya.
And, as if discovering the world’s largest underwater cave system were not amazing enough, what it contains is equally mind-blowing. You see, the Gran Acuifero Maya scientists have found an unparalleled treasure trove of archaeology, both human and animal. So far, the cave complex has offered up around 200 separate sites of archaeological significance, some dating back as far as 15,000 years.
In January 2018 Guillermo de Anda, leader of the Gran Acuifero Maya project, spoke to international news agency Reuters about the implications of the discovery. He explained, “It allows us to appreciate much more clearly how the rituals, the pilgrimage sites and ultimately the great pre-Hispanic settlements that we know emerged.” And he added, “I think it’s overwhelming. Without a doubt, it’s the most important underwater archaeological site in the world.”
The latest phase of the Gran Acuifero Maya project to explore the vast cavernous complex commenced in March 2017. Highly trained and experienced cave divers were crucial to the endeavor; and it took ten months of hard and sometimes dangerous work to find the elusive link between the cave systems.
What’s more, for Robert Schmittner, the Gran Acuifero Maya director of exploration, this was the culmination of 14 years’ work spent looking for connections between the cavern systems. So, now that the link has been established, the name of the larger of the two complexes, Sac Actun, today officially identifies the entire underwater cave network.
Speaking to National Geographic magazine in January 2018, Schmittner said, “This is an effort of more than 20 years of traveling hundreds of kilometers of caves submerged in Quintana Roo mainly, of which I devoted 14 to explore this monstrous Sac Actun system. Now, everyone’s job is to keep it [up].”
But it’s farther back in time that the story gets even more fascinating. Why? Because the Yucatán headland that lies above the caves was once home to the mighty Mayan civilization. What is known as the classic period of the Mayas’ history, when the Mesoamerican people had developed a highly sophisticated network of cities, lasted from around 250 to 900 A.D. But after this, the awe-inspiring Mayan cities were abandoned, and the reasons for this are still being debated today.
In fact, the Mayan territory stretched across much of Mexico and Central America, and the architectural and artistic achievements of this civilization are legendary. Interestingly, too, the aforementioned cenotes had a particular significance for the Maya people. The Yucatán Peninsula area has few rivers and lakes, so the cenotes were often important sources of fresh water and encouraged settlement.
And, as well as having a practical use for the Maya, the cenotes were regarded as sacred and spiritual. Mayan culture saw these sinkholes as entrances to the world of life after death. The people therefore performed rituals that centered on the cenotes, including human sacrifices to Chaac, the god of rain.
Yet in addition to featuring artifacts from the Mayan era – of which we’ll see more later – the immense caves explored by the Gran Acuifero researchers have an archeological story that stretches much further back in time. What’s more, this history highlights the fact that the cave system has been incredibly well preserved by natural forces. During the Pleistocene period, from 2,588,000 to some 11,700 years ago, when the Earth was heavily glaciated, many parts of these caves would have been dry for much of the time.
However, when the glaciers melted and water levels around the planet rose by as much as 300 feet, the caves would have flooded. And this deluge – more than 11,000 years ago – created excellent conditions for preserving some extraordinary remains of megafauna. These animals included heavyweight beasts that once roamed the Yucatán headland but which have long since been extinct.
Indeed, some of the bones uncovered in the Sac Actun caves have been scientifically dated as being 15,000 years old. The creatures in question included gomphotheres – animals that resembled elephants, although they were not from the same family as the species we know today. Other animals that died in the caves included giant sloths and bears.
But it was not just animal remains that the Gran Acuifero Maya project came across. The explorers also found evidence of some of the earliest human settlers to congregate in this region of the Americas. One human skull, now coated with limestone deposited by rainwater, was identified as dating back an incredible 9,000 years.
Meanwhile, of the 200 or so sites of archaeological significance that have so far been found in the Sac Actun cave complex, about 140 contain artifacts from the Mayan era. Fascinating manmade objects that have thus far been discovered include a mask of Ek Chaub, the Mayan god of trade.
Further discoveries have included a huge range of Mayan ceramic objects. The Maya were, it’s worth noting, renowned for their exquisite pottery, which included intricately decorated vessels used by the elite for drinking chocolate. Other, more commonplace items, such as bowls and jugs used by ordinary folk, would have been much simpler in design.
Another amazing find was a shrine that was apparently dedicated to Ek Chuaj, the Mayan god of war and commerce. This spiritual relic even features a stairway built into the side of the cenote that houses it. Elsewhere, the explorers have also come across burnt human sacrificial bones and wall art submerged in the caves.
Another of the aims of the ambitious Gran Acuifero Maya project has been to explore ancient societal connections. In particular, the archaeologists are keen to dig up any evidence of past interactions between the Mayan people and early humans in the region. For while some 140 items have, as mentioned, been dated to Mayan times, about 60 are believed to date from between 6,000 and 12,000 years ago.
Despite all of the great work done so far, though, the Gran Acuifero Maya mission is far from complete. Not only is there more archaeological work ahead, but there are other cave systems to explore under the Yucatán Peninsula. And it is possible that those systems have links to Sac Actun. If so, then this will increase both the spread of the known cave complex and our understanding of Mayan culture. Needless to say, it will be fascinating to see how it all unfolds.