We were called by a team of biologists who have been studying the importance of an unknown cave located in Izabal, Guatemala. They are worried about the fate of the natural ecosystem that lives inside the darkness of the cave since it has been polluted and neglected by the local people living close to it. We prepared our photography equipment to document biodiversity. We were amazed by how diverse the cave is, as we saw about ten bat species, some arachnids, specialized reptiles, some snails, between other creatures. In fact, thousands of bats surrounded us, guided by their echolocation and we experienced their daily flying routine around the chambers of the cave. Walking through the darkness wasn’t an easy task, due to the floor covered in wet mud, and air humidity reaching 90%. The amazing sound of thousands of bats heading out of the cave at dawn was worth all the difficulties.