Located in Tambon Ngao in the vicinity of Khlong Phrao National Park, the steep Ngao Waterfall can be seen from a great distance away because of its commanding height. The area is home to a unique species of crab. Known to locals for years as Pu Chao Fa. This fresh water crab has just been recently classified by the scientific community and added to the world's list of shellfish. These crabs, easily recognised by their white bodies and dark purple mouths, live in crevices or under dry leaves along the banks of the small creeks which run from the waterfall. Interestingly, the biologist who first classified this species, Professor Phaiboon Naiyanet from Chulalongkorn university, named the crab Phricotelphusa Sirindhorn in reverence to Her Royal Highness, Princess Sirindhorn.