Records of the Pleistocene
The Gruta do Lago Azul, or Blue Lake Grotto, is one of the largest flooded caves on the planet. To reach the lake, visitors descend a steep, man-made staircase of nearly 300 steps, which is equivalent to a 12-story building. The cave's main entrance is a circular opening approximately 40 meters in diameter. This entrance allows sunlight to penetrate deep into the cavern, illuminating the lake below. The grotto itself is a natural monument, protected by Brazil's Institute of National Historical and Artistic Heritage since 1978 to preserve its fragile limestone formations.
The cave's most significant scientific feature lies preserved at the bottom of its lake. In 1992, a Franco-Brazilian diving expedition discovered thousands of animal bones resting on the lakebed. These were not modern animals, but the remains of giant Pleistocene megafauna that lived more than 10,000 years ago. Paleontologists identified fossils from massive ground sloths and saber-toothed cats. The unique mineral composition of the water, containing compounds like magnesium sulfate, inhibits bacterial decomposition, which has allowed these ancient skeletons to remain in a well preserved for millennia.