A team of Czech speleologists made a groundbreaking discovery in Albania several years ago, stumbling upon a vast underground system of hot springs that ultimately led them to the world’s largest known subsurface thermal lake.

According to Marek Audy, a speleologist and head of the Neuron Atmos Expedition, the team followed a high column of steam rising from the limestone massif and discovered an abyss over 100 meters (328 feet) deep, which they named “Atmos.” At the bottom of this abyss, they found a strong thermal inflow and a massive lake, later named Lake Neuron after the Czech science foundation that sponsored the expedition. The lake is situated 143 meters (471 feet) beneath the surface.

During their initial expedition, the team lacked the necessary instruments to take precise measurements of the lake, so they returned a few years later with more funding and advanced scientific equipment. As Richard Bouda, a photographer and speleologist on the expedition, explained to Euronews, “We created a basic map using our equipment during the initial exploration and immediately realized we had discovered something extraordinary.” With the help of the Neuron Foundation, they used a mobile LiDAR scanner to accurately measure the cave and lake area and collaborated with hydrologists to analyze the underwater portion of the lake using sonar technology.

The team conducted a hydrogeological analysis during the second expedition to confirm the lake’s dimensions, which measured 138 meters (453 feet) in length, 42 meters (138 feet) in width, and had a total circumference of 345 meters (1,131 feet). The lake holds 8,335 cubic meters (294,348 cubic feet) of thermal mineral water, according to a Neuron statement. To put that into perspective, it’s over three times the volume of an Olympic swimming pool, and its size is comparable to being three times the size of the main hall in Prague’s National Theater.

As Bouda told Radio Prague International, “The surrounding springs are fed with water from the lake, thanks to the scientists we work with.” He added, “We believe this discovery could contribute to the protection of the area and a better understanding of its hydrology, as the connection between these underground waters and the surface is still unknown.” Lake Neuron is located in the Vromoner region along the Greek-Albanian border, an area that has received limited scientific attention due to historical tensions between the two countries.

The discovery of Lake Neuron is significant, as Audy told National Geographic, “It could have a huge impact on understanding underground ecosystems and geological processes.” The team plans to explore other parts of the cave, learn more about the geology and biology of the area, and uncover its secrets. While the world is focused on space exploration, it’s essential to remember that there is still much to be discovered about the land beneath our feet.

The discovery of Lake Neuron is a testament to the importance of continued exploration and research into our planet’s uncharted territories. As the team continues to study this natural wonder, they may uncover even more secrets about the world’s largest underground thermal lake and its role in the region’s hydrology.