Alishan — "Mount Ali" — is Taiwan's most-visited national park.
The area has been settled by Taiwanese aborigines since time immemorial, but ethnic Chinese began settling only in the 19th century. Development really took off only when the Japanese completed the Alishan Forest Railway (1912), a remarkable narrow-gauge train originally built for logging the area's giant cedars. By the 1970s, logging had pretty much ended and tourism had become the area's primary earner, and the entire area was declared a "national scenic area" in 2001.
Alishan is not a single mountain, but a range on Taiwan's spine, averaging 2,500 meters in height and with the highest peak Datashan (大塔山) reaching 2,663 meters. Taiwan's highest mountain, Yushan (3,952m) is easily visible from Alishan.
Flora and fauna
Due to its elevation, Alishan's flora are more temperate/alpine than tropical, and the slow transition from bananas and palms to evergreens on the way up is interesting to watch. The dominant feature are giant Taiwanese red cypresses (Chamaecyparis formosensis), some of which have been growing in the area for well over 2,000 years, although most are now managed forests for logging. In spring, crowds flock to view cherry blossoms, while in summer the mountainsides are blanketed with orange montbretia blossoms.
Due to its elevation, Alishan is considerably cooler than the coast, with daytime highs averaging 14-24°C in summer and 5-16°C in winter. Even for a mountain, Alishan's weather is extraordinarily rapidly changing: an average day starts with a cloudless morning, theatrically dense clouds of rolling mist by noon and ends with a lightning storm and torrents of rain before repeating all over the next day. Humidity is always very high, and indeed most surfaces in the park seem to be covered with a layer of luxuriant green moss.
The Alishan Mountain Railway from Chiayi has recently opened, but it will not get you all the way to Alishan; it only goes as far as 'Fenchihu'/Fenqihu (奮起湖). It was recently described as permanently closed, but newspaper reports in the local Chiayi newspapers in January of 2014 reported the length between Fenqihu and Alishan would eventually reopen, perhaps in two years' time. As recently as 23 April 2013 some travel guides were reporting the rail line was permanently closed. Apparently the washouts and landslides in 2010 took out too much of the track areas and it was uneconomical to repair, but politicians have decided to repair it anyway. The only other option is by coach or van private tour. Coach situation is bad - we counted mover 100 coaches at Alishan before we left at 9am in morning and stopped counting at 100 more on road down to Chiayi. You need a strong constitution for that 3 hours of very winding mountainous road. The "Alishan Forest Railway" (in the hills around Alishan township) is still operating normally but can be very crowded - especially on the two "view the Sunrise" specials at 4am in morning ! Be warned -"cloudy - cannot see sunrise". Tickets for the sunrise train can be bought one day in advance from 13:00 to 16:30 and also on the same day from 30 mins before departure. The number of available seats for the next morning are written on a whiteboard after 16:30. There will also be an electronic counter above the ticket queue in the morning showing the number of tickets left. The departure time depends on the sunrise time, both are posted outside the ticket office.
Take the famous Alishan Forest Railway narrow-gauge train from Chiayi station (the old one, not the new HSR station at Taibao). A one-way costs NTD$399 (about US$13) and takes around 3.5 hours (currently NT$240 to Fenchihu). The train passes through the scenic village of Fenchihu (奮起湖) halfway up and the village of Ruili (瑞里) is also accessible (several km away) from Jiaoliping (交力坪) station. Don't miss this trip, especially if you're a train or architecture buff, as the line is largely the same as it was before WW2 — but you might want to consider a bus for the way back (it takes about 4.5 hours for the return trip).
As of 2014, there is a daily departure from Chiayi at 9 AM, returning from Fenchihu at 2 PM. On Saturdays there is an additional departure from Chiayi at 2 PM, and on Sundays a departure from Fenchihu at 12.30 PM. Note that trains can be sold out for days in advance, if so you might be better off trying your luck coming downhill (get the bus up to Fenchihu). During peak periods like summer and the cherry blossom season trains can get very crowded, so book ahead by calling operator Hungtu Alishan at (05)225-1978, preferably in Chinese, and show up at least 30 min before departure to collect your tickets. Alternatively, there are sometimes "scalpers" standing outside the ticket window selling tickets at-cost, in the hope that you will also book a room in the hotel they work for or if seats are sold out on the train, they still sell standing only tickets (managed to get midweek in cherry blossom season 20 minutes before leaving) and if you're lucky you will get a seat anyway. In Chiayi station, note that the Alishan ticket counter is on the outside of the building, separate from the ordinary TRA counters. To continue you will need the Bus (minivan) connecting Fengqihu and Alishan. There are daily departures at 10:30 from Alishan and 14:40 from Fenchihu (on the weekend there are more). These busses can only be reserved on the same day. 
Note: As of December 2009, the railroad was closed due to major repairs after a typhoon struck. In June 2010, the Jhushan Sunrise-Watching Line (祝山觀日線) and the Divine Tree Line (神木線) within the recreation area re-opened, but the line down the mountain is not expected to re-open until late 2015. However, the line has been repaired and reopened between Chiayi and Fenchihu as of early 2014. Update (Feb 2014): Locals state that the re-opening of the railway from Chiayi to Alishan will take an additional 2 years, but people are already using it to get to lower elevation places such as Fenchihu, since that portion of the line has reopened.
February 2015: the train operates from Chiayi to Fenchihu (or Fenqihu). On the weekdays, it leaves Chiayi at 9am and on the weekends at 10am. It costs 240NT$. It takes 2h45. If the seats are sold out, you can still buy no seat ticket. You can call to make reservation.
Very comfortable buses from Chiayi to Alishan leave roughly hourly, take just over two hours and cost NT$221 each way. However, the route isn't quite as scenic, with more tea plantations and small villages than cliffs and mountains. The bus ride can also be quite windy, so be careful if you have motion sickness.Buses stop at Ruili on the way. Note: The last bus to Alishan from Chaiyi is at 2PM. After that the only way to get to Alishan is by taxi which will cost $1600NT.
there is daily bus from sun moon lake to alishan. time: 8am and 9am, cost: 350NTD. it takes 3.5 hours
The last bus back to Chiayi leaves at 17:10. Buses leave from the 7-11 store across from the tourist information center. Tickets are also purchased inside the 7-11.
Note: Most take bus from Chiayi rail station to Alishan. As of Oct 2011, there is a direct bus service from Chiayi HSR station to Alishan. Only two buses a day, between 10 am to 1130am. Go to the visitors information counter at Chiayi HSR station for more info. Cost is less than NT$300 one way, takes about 2.5 hrs. If you get the driver who drives like a Daytona driver (by the name of Mr Luo), get ready the motion sickness pills and the journey is about 2 hrs including the toilet breaks.
Entry to Alishan costs NT$150 per person if arriving on public transport, NT$200 if arriving by car, charged on arrival.
If you show a student ID the cost is NT$100.
February 2015: It costs 200NT$ to enter by bus on weekends and holidays and 150NT$ on weekdays.
The Alishan Forest Railway has three very popular spur lines within the recreation area.
Trails around Alishan are ridiculously well signposted: every intersection of two paths not only has signs in Chinese and English, but a map pinpointing your exact location and all possible routes. You can also pick up an English map from the tourist office. All the main routes are very well maintained, with stairs for steeper sections, guard rails, etc.
A newly opened trail, about 4 hours one way, connects Fengcihu and Ruili through a scenic bamboo forest straight out of a kung-fu movie.
Sights around Alishan are signposted in Chinese, English and Japanese, and as you walk around the trails you'll find that nearly every tree of size, age or unusual shape has been dubbed with a fanciful moniker like "Elephant Trunk" or "Three Generation Tree".
The hardcore hiker or sports enthusiast will likely find Alishan's offerings rather too tame, and might do better to go conquer Yushan next door instead.
If you stay overnight in Alishan, you can avoid crowds of tourists who do day trips. You should pretty much have the place to yourself by late afternoon. Wear comfortable shoes with good traction as the steps can be wet and mossy.
You can leave your luggage for free at the Visitors Center (ask the staff) and take it back before 5pm.
The hike from Fenchihu to Rueili goes through bamboo forest. You will have the trail for yourself. The trail is really well marked and there are maps everywhere. From the train station in Fenchihu, head up to the hill and left on the road. After the parking lot, you will find the trailhead. It takes around 2h30 from Fenchihu to Rueili, but probably more coming back because Fenchihu is higher than Rueili. There is no bus in Rueili. If you want to hitchhike to Fenchihu, when you arrive at the end of the trail, turn right and follow the sign for the Tourism Information. After 1km, you will reach an intersection and the road for Fenchihu/Alishan will be at your right. It takes 35 minutes by car. There is a few traffic, so don't arrive there too late! If you want to head to Chiayi, hitch to the left. It's a 45km. You can leave for free your luggage at the train station (ask the staff) and take it back before 4:30pm.
Alishan is famous for all sorts of mountain produce, notably tea (see Drink) and wasabi, as well as carvings and handicrafts made from red cypress. Souvenir shops also sell tasty cookies and pastries flavored with ashitaba (明日葉), a medicinal herb reputed to give long life. The name is Japanese for "tomorrow leaf", as (according to legend) if you pluck a leaf early in the morning, a new one will replace it by the next day.
For a meal on the train, don't miss the Fencihu lunch box (奮起湖便當 fencihu biendang), which has a deep-fried cutlet, Taiwanese sausage and a selection of mountain veggies on rice. Vendors come onto the train to sell them at Fencihu station (NTD100 a pop).
Stalls selling noodles, rice dishes and basic street food can be found at the Alishan main square, at Jhushan and the Jhoushen Temple.
While you are waiting for the sun to rise, a hot drink from the vendor will warm your hands. Also try the egg crepe, scallion pancakes and French toast. Hot Clear soup with blood rice cake is also available. Hot Sakura flavoured honey in the early morning is great too.
Alishan's main square has half a dozen largely identical restaurants specializing in hotpot (火鍋), using mountain vegetables and mountain game like deer and wild boar. Most cater mostly to groups and thus offer vast spreads (eg. 10 dishes for $1000), but if you stick to the menu, a "small" pot for two-three goes for around $300.
Alishan is famous for High Mountain Oolong (高山烏龍 Gau-shan wulong) tea and you'll see plenty of plantations on the way up. There are a number of tea shops in the main village that will serve up a pot the traditional way for $200 or so. They will also let you try a number of teas for sale, and this is a good way to pass the evening. But this is with the expectation that you will buy something. Teas are mostly sold in vacuum sealed bags of 150g, and usually will cost between $400-$800, although some can be as high as $3000 for this amount.
Nightlife in any sense is virtually nonexistent, but all restaurants are happy to sell you a beer and you can pick your own poison at the convenience stores.
Most of Alishan's accommodation is clustered around the main Alishan railway station, which is very convenient for eating and shopping, but means a one to two km hike (or short train ride) for visiting the park itself. They can be found in the hotel area, which is behind the visitor center, the stairs down can be found just to the left of the building. While touts meet incoming trains, it is best to reserve the hotels ahead of time, since on weekends (Fri, Sat) and holidays most rooms will be booked almost every day of the summer. Weekday rates are much lower.
A few hotels can be found elsewhere in the park.
Camping is not permitted anywhere within the Alishan Scenic Area. If you have your own car, there are a few campgrounds within striking distance outside the park, notably at Dinghu (頂湖).
There are no dangerous animals or unusual health risks around Alishan. Be prepared for rain at any time and bear in mind that, especially outside summer, it can be quite cold. It is about 10C colder in Alishan than Chiayi.
At the risk of stating the obvious, while the trails are exceptionally well guided during the daytime, there is next to no lighting — so head back when the night starts to fall.
As of 10 Oct 2011, there is a direct bus service (員林客運) from Alishan to Sun Moon Lake and vice-versa. 2 buses a day, leaves Alishan at around 1pm and 2pm. Cost is about NT$350 one way. Check with Alishan Visitors Centre for more info. You can also choose to arrange for a cab there. A cab from Alishan to Sun Moon Lake is NT$3000 one way.
February 2015: A direct bus to Sunmoon Lake leaves at 1pm and 2pm. It costs 332NT$ and takes 3h30. You need to buy your ticket the same day at 9am in the restaurant at the left of the 7/11.