This stunning slow motion footage shows how bats use echolocation to find water. It was made by scientists at the Max Planck Institute for Ornithology whose work was published in Nature Communications today. We know how bats echolocate to hunt insects, but this is the first study to show how they recognise large, flat objects like ponds. Moreover, by testing young bats that had never encountered a pond or river before, the researchers show that bats seem to have a built-in ability to recognize these important features of their environment.