While visiting Mulu national park, we had the opportunity to go adventure caving. This meant entering a cave in the evening with a guide, with lots of clambering up rocks, squeezing through gaps, abseiling down mini-cliffs - all in the pitch black! The cave we went to was racer cave - so called because of a population of racer snakes who lie waiting for bats to fly by so they can eat them. Also saw a giant poisonous centipede, some massive spiders, and thousands of bats! Because we were there at dusk, the bats were circling the cave getting ready to head out for dinner. There were literally tens of thousands of them in the cave, all swooshing about around us, it was awesome!