At about 870 meters in elevation, Menghuan Lake is located at the southeast foothills of Qixing Mountain. A rare aquatic fern, Taiwan quillwort, grows in the Lake. It is a relatively low-latitude region for quillwort in the world. Aquatic fern, such as Taiwan quillwort, is very hard to find; to preserve the national treasure, Menghuan Lake has been set as an ecological preserving zone. General tourists are not allowed in the Menghuan Lake area; they can view it from a sightseeing deck next to the Lake.
Compared to other places, Menghuan Lake has more rain in spring and summer. When the rainy season or heavy rain passes, the Lake will overflow. If it happens to encounter the mist on the mountain, the beautiful lake surface accompanied by the mist will make you feel that you are in a secret fantasy land in the fairy tale.