MEXICO CITY (Reuters) - A group of divers has connected two underwater caverns in eastern Mexico to reveal what is believed to be the biggest flooded cave on the planet, a discovery that could help shed new light on the ancient Maya civilization. 
 
 The Gran Acuifero Maya (GAM), a project dedicated to the study and preservation of the subterranean waters of the Yucatan peninsula, said the 347-km (216-mile) cave was identified after months of exploring a maze of underwater channels. 
 
 Near the beach resort of Tulum, the group found that the cave system known as Sac Actun, once measured at 263 km, communicated with the 83-km Dos Ojos system, the GAM said in a statement. For that reason, Sac Actun now absorbs Dos Ojos. 
 
 GAM director and underwater archaeologist Guillermo de Anda said the “amazing” find would help to understand the development of the rich culture of the region, which was dominated by the Maya civilization before the Spanish conquest. 
 
 “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,” he told Reuters. 
 
 The Yucatan peninsula is studded with monumental relics of the Maya people, whose cities drew upon an extensive network of sinkholes linked to subterranean waters known as cenotes. 
 
 Some cenotes acquired particular religious significance to the Maya, whose descendents continue to inhabit the region. ||||| Explore the World's Largest Underwater Cave 
 
 
 
 Click here to read World's Largest Underwater Cave Discovered. January 17, 2018 - The world's longest underwater cave has been discovered near the city of Tulum, on Mexico's Yucatán Peninsula. The new discovery connects two previously known flooded caves into one 215-mile-long stretch. The cave holds an important large fresh water reserve that supports great biodiversity. Hundreds of archaeological sites exist in the cave, including evidence of America's first settlers, Mayan culture, and extinct animals. 
 
 Last Wednesday, after ten months of work, the Underwater Exploration Group of the Great Maya Aquifer Project (GAM) found a connection between two of the most extensive flooded cavern systems on Earth—Sac Actun and Dos Ojos, both in Mexico's Yucatán Peninsula—now forming the world's largest known flooded cave, with a length of 215 miles. 
 
 "This immense cave represents the most important submerged archaeological site in the world, since it has more than a hundred archaeological contexts, among which is evidence of the first settlers of America, as well as the extinct fauna and, of course, of the Maya culture," says Guillermo de Anda, a National Geographic explorer and director of the GAM. 
 
 This phase of the project began in March 2017 with the work of GAM director of exploration Robert Schmittner and a team of divers specialized in caves. Schmittner had been looking for this connection for 14 years and adding new mapped tunnels and galleries to this water labyrinth. 
 
 So far, the 167-mile-long Ox Bel Ha System, located south of Tulum, Mexico, was the longest. The Sac Actun System, located northeast of Tulum, was ranked second, at about 163 miles. 
 
 The third on the list was the Koal Baal System, with 57 miles; and the fourth, the Dos Ojos System, with 52 miles. Now, as a result of the exhaustive exploration, the latter is added to the Sac Actun System. 
 
 According to the rules of caving, when two cave systems are connected, the largest cave absorbs the smallest, so the name of the latter disappears. 
 
 The next goal will be to connect Sac Actun with the other three underwater cave systems, which are very close to each other and located in the municipality of Tulum. 
 
 According to data from the Quintana Roo Speleological Survey, there are 358 submerged cave systems in the north of the state, which represents nearly 870 miles of flooded passages of fresh water. 
 
 "The Mother of All Cenotes" 
 
 As a result of this same search, the exploration group of GAM has registered another important system with a length of 11 miles, until now called "the mother of all cenotes." It has a maximum depth of 65 feet and is located north of Sac Actun. From what is known so far, it is an individual system, but the team of explorers may be able to connect it to Sac Actun as well. 
 
 "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]," says Schmittner. 
 
 These "hundreds of kilometers" of underground passages have become true tunnels of time, guarding the remote and recent history of this Mexican region. 
 
 Treasure of Biodiversity 
 
 Another feature that makes this finding valuable is that it supports a great biodiversity that depends on this enormous system and represents an extensive reserve of fresh water that has given life to this region of the Yucatán Peninsula since time immemorial. 
 
 This and other GAM efforts seek to better understand the subsoil, its biodiversity, and the relationship human beings have with these ancestral waters to achieve an adequate understanding of the natural resources that depend on this aquifer. 
 
 The next phase of this ambitious project includes an analysis of the water quality of the Sac Actun System, as well as a study of its biodiversity and its conservation, in addition to giving continuity to the mapping and detailed record of submerged archaeological contexts. 
 
 Tulum has become a mecca of cave diving. Underwater explorers from different latitudes have dedicated a great part of their lives to exploring this landscape. Among them, cave explorer Bil Phillips co-founded the Quintana Roo Speleological Survey, a database with detailed maps of these complex systems that is a tool to understand and protect the area. 
 
 Phillips, who died in November 2017, explored this underwater world until his last days. For more than 40 years, he dedicated himself to understanding the depths of the site through the investigation of these ancestral waters. The GAM team dedicated their achievement to Philips, the underwater cartographer of the project. ||||| A team of experts from the National Institute of Anthropology and History (INAH) has discovered a link between two systems of flooded caverns that together form the world’s largest underwater cave. 
 
 The multidisciplinary team made the discovery during work on the Great Mayan Aquifer (GAM) project, in which archaeologists, biologists, underwater photographers and cave divers are exploring, documenting and mapping the extensive subterranean network of water deposits on the Yucatán Peninsula. 
 
 GAM project director Guillermo de Anda told the newspaper Milenio that the discovery of the connection between the 263-kilometer-long Sac Actun system and the 84-kilometer Dos Ojos system in Tulum, Quintana Roo, was made on January 10 following 10 months of intense work. 
 
 The interconnected system measures 347 kilometers and has an average depth of 20 meters, although in some sections it is as shallow as two meters and in others as deep as 100. 
 
 In accordance with speleology conventions, the combined network will be named after the larger of the two systems: Sac Atun, which in the Yucatec Maya language means the White Cave. 
 
 “Without a doubt, it’s the most important submerged archaeological site in the world,” de Anda said. 
 
 “We’ve recorded more than 100 archaeological elements: the remains of extinct fauna, early humans, Mayan archaeology, ceramics and Mayan graves. It’s also very significant that this discovery enables us to see the possible patterns of past settlement. From the Pleistocene through to the ancient Mayans and up to the colonial era, they developed parallel to this enormous flooded fresh-water cave,” he added. 
 
 De Anda also said that within the underwater system there are dry and partially dry caves where the research team has documented age-old modifications that include walls and staircases and discovered cave paintings and other signs of ancient human presence. 
 
 Documentation of the extensive cave system is a great achievement as the aquifer represents one of the final frontiers of exploration, the underwater archaeologist said. 
 
 “INAH authorities are conscious of the challenge represented by properly documenting, studying and recording all the [different] elements and placing them under the same lens in order to stop seeing them in an isolated context [but rather] make a comprehensive interpretation,” de Anda said. 
 
 German explorer Robert Schmittner, who leads the diving team, said the discovery of the link between the two systems is the result of years of hard work and his team’s dedication, passion and desire to find it. 
 
 “It’s a titanic effort from the whole team . . . I didn’t rest for 14 years until I found the interconnection . . .” Schmittner explained. 
 
 However, de Anda said that there is still a lot of work to be done to better understand the value of the natural resources, the morphology of the Yucatán Peninsula subsoil and the biodiversity of the subterranean cave networks. 
 
 Another challenge is finding whether any links exist between Sac Actun and three other nearby underwater cave systems. One located to the north of Sac Actun is considered “the mother” of the cenotes, or sinkholes, and until now at least, believed to be an independent system. 
 
 According to data from the Quintana Roo Speleological Survey, there are 358 underwater cave systems in the north of the state alone. 
 
 Together, they are made up of around 1,400 kilometers of underwater passages including the 270-kilometer-long Ox Bel Ha system located to the south of Tulum. 
 
 Source: Milenio (sp) ||||| The search for the world's most extreme measurements - biggest, highest, tallest - tends to focus above ground, gazing at towering mountains and epic canyons. 
 
 But the latest global peak statistic has come from under the soil, in the subterranean depths of Mexico's Yucatan Peninsula. 
 
 There, in the famously porous terrain above which the Mayan civilisation once thrived, is what is now considered to be the planet's longest underwater cave system. 
 
 A diver exploring Sistema Sac Actun Credit: HANDOUT 
 
 This is not, technically, an uncovering of a new wonder - more a joining of dots. 
 
 In recent days, divers have confirmed what had been suspected for a while - that the Sistema Sac Actun (a submerged labyrinth which stretches out for 164 miles) and the Dos Ojos system (shorter, but still impressive at 52 miles in length) are one and the same thing, connected by a previously unsurveyed channel. 
 
 Together, this pair of vast limestone wormholes add up to 216 miles of below-the-surface space - a number which makes their combined size greater than that of the Sistema Ox Bel Ha (also in eastern Mexico; 168 miles), which was previously thought to be the yardstick for underwater networks. 
 
 The cave stretches for a staggering 216 miles Credit: HANDOUT 
 
 The discovery is the result of years of hard work by Gran Acuifero Maya, a project which focuses on the study and preservation of the subterranean waters of the Yucatan. 
 
 The finding has been hailed as "amazing" Credit: HANDOUT 
 
 The finding has been described as "amazing" by Guillermo de Anda, who is both the director of Gran Acuifero Maya and an underwater archaeologist. 
 
 It is the result of years of hard work Credit: HANDOUT 
 
 He says that expanded knowledge of the cave system will allow for a greater understanding of the Maya people, who thrived in the region before prior to the Spanish conquest of Central and South America in the 16th century. 
 
 "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," he told Reuters. 
 
 The Maya considered cenotes to be holy sites Credit: GETTY 
 
 The Maya held the "cenotes" - giant sinkholes - of their region in high esteem, regarding them as holy sites and portals to communication with the gods. 
 
 Religious objects and human skeletons have been found at the bottom of some of these sinkholes, including the Sacred Cenote at the historic city of Chichen Itza - leading to the theory that they were used by the Maya for human sacrifice. 
 
 One of the Yucatan Peninsula's biggest sinkholes is the Gran Cenote - which sits three miles west of the popular tourist town, Tulum. This is also part of the Sistema Sac Actun, and has been used as a gateway for divers charting its many twists and turns. 
 
 The beach at Tulum Credit: Monica and Michael Sweet/M Swiet Productions 
 
 This is not the first time this watery maze - whose name translates from Spanish and Yucatec Maya as "White Cave System" - has been found to have hidden contours. 
 
 In 2007, it was revealed that the Sistema Nohoch Nah Chich, previously thought to be separate, was also linked to the Sistema Sac Actun. 
 
 It is not, however, the longest cave system in the world. 
 
 While its size makes Sistema Sac Actun the longest underwater cave network, the longest on the planet is the Mammoth Cave complex - which is riddled into the hillsides of southern Kentucky, and is thought to extend for 405 miles.
– For Robert Schmittner, it was a long time coming. "I didn't rest for 14 years," the diver tells Mexico News Daily. Schmittner is the director of exploration for the Great Maya Aquifer Project, which on Jan. 10 discovered the longest underwater cave on Earth. Divers for the project made the discovery by confirming something that—as per the Telegraph—had been long suspected: the 163-mile-long Sac Actun system and 83-mile-long Dos Ojos system of Mexico's Yucatan Peninsula are actually connected. Sac Actun's underwater cave system now absorbs Dos Ojos, becoming the record-setting, 216-mile-long Sac Actun system, Reuters reports. According to National Geographic, it's now 49 miles longer than the previous record holder and could get even bigger as divers continue to seek connections to other flooded cave systems in the area. "This immense cave represents the most important submerged archaeological site in the world, since it has more than a hundred archaeological contexts," the project's director, Guillermo de Anda, says. Those contexts include extinct animals and possibly signs of the first American settlers, but also new information about the ancient Maya civilization. “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,” de Anda tells Reuters. Sinkholes leading to underground caves had religious significance to the Maya, and de Anda's project has found ancient walls, staircases, and paintings in some of the caves that aren't completely flooded. (A skeleton found in an underwater cave is one of the oldest in the Americas, so it's too bad thieves stole it.)