The 25¬kilometre road to Thi Lo Su waterfall, the sixth largest waterfall in Asia, in Umphang district of Tak province, will re¬open on Thursday after being closed for four months for the rainy season, the Department of National Parks, Wildlife and Plant Conservation announced. The road, which starts from the Huay Nong Luang forest protection unit, can be used only by four-wheel drive vehicles during the wet season and was closed this year from June 1 to Sept 30 inclusive . Closing the road also assists regeneration of the forest and allows wildlife to breed without disturbance. Thi Lo Su waterfall is 900 metres above mean sea level. It is where the Huay Klo Tho stream cascades spectacularly over a steep cliff, surrounded by dense forest.