Anuradhapura, Sri Lanka.
While visiting Isurumuniya Vihara, the rock temple, I heard telltale squeaking lots of it. It came from a crevice in the rock, just beside the temple. I approached in disbelief... and ran back to the van to get my telephoto. Inside the crevice, where it is forever shaded but only inches from the part of the stone that is constantly sun-baked, the rock was covered in a fluttering, squeaking, furry mantle... Dozens if not hundreds of bats roosted huddled for the day. I never imagined I would see such a thing without having to dive deep into a cave far from sunlight and human presence! I was completely fascinated I love bats, even though such a swarm of them is borderline creepy (I later caught a much more hair-rising glimpse of another bat-inhabited dark space, in a temple, in the gap between two walls).
I did not use a flash, naturally, but the telephoto allowed me to zoom in close enough to crop out any bright areas, forcing the film to pick up details in the darkness. I myself only saw the details after the picture was printed, though. It was one of those happy surprises I like so much about film