Umphang is a small district by the Thai-Myanrnar border in Tak province. It is thought the name 'umphang' is a corrupted form of `urripha', a bamboo tube used in the old days by Burmese traders carrying travel documents to cross into Thailand. This district is mountainous and mostly blanketed with thick, green forestland.Thi Lo Su is Thailand's highest waterfall and is considered the sixth biggest waterfall in the world. Unsurprisingly, Umphang has become Tak's foremost attraction for adventurous and nature-loving tourists, both Thais and foreigners alike. In the local language, 'thi lo' means waterfall, and 'su' means loud, so Thi Lo Su is the waterfall that makes a loud noise, due entirely to its size and thunderous flow of cascading water that falls some 200-300 meters.The winding mountain road that accesses Thi Lo Su waterfall is naturally decorated, on both sides, by colorful plants, each season displaying it own particularly attractions.During the rainy season from June to November Thi Lo Su takes on a special beauty because the rushing waters are at full flood, cascading over a wider stretch of cliffs than at other times of the year.In winter to summer between December and May it is easier to visit Thi Lo Su because potholes in the roads should have been repaired after a rainy onslaught. Water levels are lower and the water's pace slower making it more accessible, and much safer, for swimming or rafting.The 1.8 kilometer nature tail to Thi Lo Su winds its way through bamboo groves and light wooded areas. Along the way, tourists can see information signs about the flora and fauna in the forest. At the waterfall, fine sprays of water offer a welcome cooling effect. And when you gaze upon the 200-400 meter wide stretch of cliff with the waters gushing down it makes you feel as though you are standing amidst a grand, tropical kingdom embraced by the magnificent world of nature.