The flues of Shuǐnǎndòng 水湳洞 are an extraordinary sight. The ruins of these massive, crumbling conduits run for miles up the mountainside from Shuinandong Smelter 水湳洞精鍊廠 and the rest of the abandoned mining complex below. Originally built to transport noxious fumes and waste gases away from the refinery—and nearby settlements like Jīnguāshí 金瓜石—these flues are reputedly the longest in the world. Like everything else on this hillside the flues are an unmitigated environmental disaster, contaminated by heavy metals and countless other poisons. Rather than clean anything up the entire area has been transformed into what must be the most egregious example of disaster tourism anywhere in Taiwan 台灣. Not far from the flues you will find Golden Falls 黃金瀑布 and Yin Yang Sea 陰陽海, both discoloured by runoff from heavy metal contamination across the region.
For reference, the flues are often referred to as the Changren No. 3 Waste Flues 長仁三坑廢煙道 in Chinese, though I believe this only refers to the flue that runs through the Gold Ecological Park 黃金博物園區.