About 4 hours one way, connects Fenqihu and Ruili through a scenic bamboo forest straight out of a kung-fu movie.
祝山
The top attraction in Alishan, everybody crowds aboard the predawn trains for the half-hour trip to this peak on the east side of Alishan, where you can see the sunrise over Yushan. If you're an early riser, you can also walk (the whole way is lit, albeit weakly), it's a not overly strenuous one hour from the 7-Eleven - this also allows you to go early before the crowds and enjoy the amazing pre-dawn twilight colours and tranquility, which you will miss if you take the train. There's a viewing platform right next to the station, but it's worth it to hike an extra 15-20 minutes past the helicopter pad to the very top, where the crowds are a little thinner. As the sun is already up behind the mountain, the sky is already quite light by the time you get to the top, and the sun is very bright when rising up -- hawkers sell disposable NT$10 eclipse-style filtered glasses, but it's better to not stare at all. On the way back, skip the train and walk back instead, it's a pleasant 3-4 km downhill hike.
There are in fact two of these, both near Shermuh station, and they can be walked in a pleasant half-hour loop. The 36 featured cypresses here are giant indeed, and many have been growing for well over a millennium. The original 52 m Sacred Tree fell in 1998 to become a massive nurse log, passing the sacred designation to the 47 m Xianglin Giant Tree. The small Cihyun Temple, which was built by the Japanese, and the Tree Spirit Pagoda are along the way. The trail is particularly magical when the mist rolls in (in October, this tends to happen in the early to mid afternoon).
姊妹潭
Two scenic little ponds in the forest. The Elder Sister Pond, the larger of the two, has a much-photographed octagonal little pavilion in the middle.