One of Japan's Three Hidden Valleys, Iya was raised into the Japanese and Western consciousness by outspoken Japanese-culture conservationist Alex Kerr. His book Lost Japan (ISBN 0864423705) presented an idyllic picture of a misty valley of thatch-roofed houses, stuck in a time warp to days gone by.
These days, much of Iya has been devoured by what Kerr calls the Moloch, with the silence broken by the sound of jackhammers as multi-lane highways and ghastly concrete hotels sprang up to serve people flocking to see the view. Still, while all the rivers have been replaced by the usual concrete channels, and the trees replaced by uniform rows of artificial cedar, some of the less-visited eastern reaches are worth visiting. (For a true taste of a Hidden Valley, Yagen Valley up north in Tohoku might be a better option.)
The valley can be divided into halves, the more populated and developed West Iya (西祖谷 Nishi-Iya), and the more remote East Iya (東祖谷 Higashi-Iya ), which is also known as Oku-Iya (奥祖谷). There are small settlements (many of them abandoned) along the highway connecting the two, but the largest on the east side is the hamlet of Mi-no-Koshi (見ノ越), near Mt. Tsurugi and the intersection of three small highways.
Getting in no longer requires a week of hiking along misty mountain trails, but remains a little more difficult than most Japanese destinations.
From Oboke you can connect to a bus through a tunnel into West Iya, but services are infrequent: there are up to eight buses per day on weekends only in the high season (April-Nov), and just four per day the rest of the time.
There are 7 direct buses daily from Ikeda's Awa Ikeda Bus Terminal (阿波池田ＢT), which pass by JR Ikeda Station and travel to West Iya either via Oboke (4 daily) or via Iyaguchi and Iya Onsen (3 daily). See Yonkoh for a timetable, in Japanese only; select "祖谷線" (the Iya Valley line) and then look for Awa Ikeda (阿波池田ＢT) or Ikeda (池田駅前) departure times. The buses terminate at Kazurabashi (かずら橋) in West Iya or Kubo (久保) in East Iya.
From Kubo, there is a connecting service via Oku-Iya Kazurabashi (奥祖谷かずら橋) to Mi-no-Koshi (見の越) at the base of Mt. Tsurugi. This service runs twice daily during weekends and vacation periods and does not run in winter. See  for more information including exact times and dates, in Japanese only.
A similar but even more restricted service is provided when coming from the north. Normally, the buses from JR Sadamitsu Station (貞光駅) do not run all the way towards the Iya Valley, but on weekends and holidays during summer there seems to be a connecting service (3 daily) to Mi-no-Koshi at the base of Mt. Tsurugi. See  for more information, in Japanese only.
If you have your own set of wheels or want to try your luck hitchhiking, Route 438 from Sadamitsu and Route 439 from Anabuki connect directly into East Iya, and offer the fastest route if arriving from Tokushima and Kansai. If you are heading to Mt. Tsurugi (剣山) from Sadamitsu (貞光), there is a regular bus service along Route 438 but only as far as the base of the mountain. Coming from Mi no Koshi (見ノ越), figure on a four hour walk down the mountain to the bus stop. Along the way, try some delicious hand-made udon noodles (手打ちうどん) at the restaurant beside the river. Note that traffic is very light, especially on weekdays, and the roads are quite narrow and twisty.
In the valley itself, public transportation is limited to a few buses a day. Car rental or hitchhiking is probably the fastest way of getting around, but hitchhikers beware: even the main highway sees only around three (3) cars per hour on a weekday, and forget it if it's raining.
It is possible to cycle the Iya Valley, but you'll need a good bike (you can carry bicycles on Japanese trains if you put them in a bike bag), a healthy pair of lungs and a genuine sense of adventure. Bring water, as even the normally ubiquitous vending machines can prove few and far between in the Iya Valley. Reduce your speed when on narrow roads with limited visibility, use mirrors to see around corners, and keep as far to the left as possible. Most of the locals are cautious drivers. If you make it to Tsurugi-san, you can turn left onto the road leading to Sadamitsu Town, which is a breathtaking 25-km downhill of switchbacks, little crumbling villages and stunning river vistas.
Iya's best-known attractions are the precarious-looking vine bridges (かずら橋 kazurabashi), which used to be the only way to cross the river.
- The most popular vine bridge is in West Iya, quite close to the main village. This is a rather large operation and not particularly scary, entrance costs ¥500 and the bridge's operating hours are officially defined as sunrise to sunset.
- The more atmospheric Oku-Iya vine bridges (奥祖谷二重かずら橋) can be found at the eastern end of the valley, before the final ascent to Mi-no-Koshi. There are two of them, namely the Husband's Bridge (夫の橋 Otto-no-hashi), the longer, higher up and thus evidently manlier of the two, and on the left the Wife's Bridge (婦の橋, Tsuma-no-hashi). These are a bit closer to the Tarzan kind of vine bridge and best avoided if you have a fear of heights, although even here there are steel cables hidden inside the vines. On the other side is an excellent campground and a beautiful waterfall. There is also a small wooden cart that can seat up to three people suspended from rope cables near the Wife's Bridge. You can go halfway across the ravine before you need to pull yourself the rest of the way with the rope in the cart, though people waiting in line often help pull at either end. Entrance ¥500, but getting here can be a problem as buses usually don't come this far.
- Chiiori House, ☎ , e-mail: email@example.com. A mountain-side thatch-roofed, traditional Japanese farmhouse, restored at exorbitant cost and described in loving detail in Lost Japan. It's open to visitors, who can work and contribute to the organization's community revitalization efforts. Run by friendly volunteers, you have to book at least a week in advance to stay overnight, and should contact them for visits of any length. No fixed fees, but a donation is expected. The easiest way to get there is via taxi from JR Oboke Station (about 45 minutes), but there are buses from Awa-Ikeda and Oboke — the Oshima Tunnel is the closest stop.
- O-Tsurugi Shrine (お剣神社). Located in Mi-no-Koshi, not far from the Tsurugi chairlift station. It's not very much to look at, but it's traditional to stop here before starting your ascent. The shrine is in fact in three parts, with one in Mi-no-Koshi, one on the trail to the top and one at the very top of the mountain.
Hiking in the valley, especially the eastern end, is quite popular and there are many trails of various lengths mapped out.
- Mt. Tsurugi (剣山 Tsurugi-san, also known locally as Ken-zan, 1955m) is the most popular hiking destination and the 2nd tallest in Shikoku (#1 being Mount Ishizuchi). The name may mean "Sword Mountain", but this is a singularly inaccurate description of this gently rounded fell, and you can even take a chairlift up most of the way (¥1000). From the chairlift terminal, it's a half-hour climb to the summit. Alternatively, if you choose to hike up or down the long way (2 hours or so), you can stop at O-Tsurugi Shrine (お剣神社) along the way for a free sip of holy sake and a quaff at a clear mountain spring with drinkable water.
- Trails radiate from Tsurugi in a number of directions, one of the most popular being across Jirogyu and Maruishi and down directly to the Oku-Iya vine bridges and campground.
- Miune (三嶺) is another popular trip, but less crowded than Mt. Tsurugi. Locals say it is the best hike to see the autumn foliage. The trail starts at the hamlet of Nagoro and takes about 2.5 hours up. The area is currently the focus of much construction with a hot spring resort, cable car and even a monorail being carved into the mountainside.
Iya doesn't have even a single chain convenience store, but there are some mom-and-pop type grocery shops in both West Iya and Mi-no-Koshi, and quite a few more souvenir shops. It's best to bring along anything even remotely exotic. You can get good supplies of groceries from Boke-Mart, the local grocery by the station at Oboke.
West Iya and Mi-no-Koshi have the usual range of rice and noodle joints, all a bit on the expensive side by Japanese standards. Try grilled amego (a local river fish) at 500 yen a pop, sold by little stands here and there.
Many places advertise Iya soba noodles, but if you've ever been to another mountain in Japan you'll recognize the topping as the same sansai mountain vegetables served everywhere else.
- Senkichi, Nishi-Iya (a little way up from Hikkyo-no-Yu Onsen). A soba restaurant easily spotted by the ninja climbing up the outside of the building. Inside it's decorated with rustic style furniture, and even a traditional sunken hearth.
Also, food and snacks can be found at Fureai Centre and Michi No Eki.
If you want nightlife, you are completely in the wrong place!
- Iya Kazurabashi Camp Village (祖谷かずら橋キャンプ村 Iya kazurabashi kyanpu-mura), ☎ . An excellent little campground in West Iya, on the south side of the river a 10-minute walk (mostly uphill) from the vine bridge. ¥500 gets you a patch of grass for the night, with beautiful views of the valley. Toilet facilities and hot water shower are provided. Staying here entitles you to a discount at the Hikkyo no Yu onsen, bringing the cost down to a more reasonable ¥700. Pick up a discount coupon from the caretaker of the campsite.
- Oku-Iya Kazurabashi Camping (奥祖谷かずら橋キャンプ). A rather basic, but magnificently placed campground located across the Oku-Iya vine bridges at the eastern end of the valley. Entry is ¥300 per person, plus the ¥500 to cross the bridge to the campsite (only once if you stay for more days). There is a separate cargo pulley system, so you can shift your supplies across the river without carrying them on your back across on the precarious vine bridge. There are only very basic toilet facilities and no showers. You can ask the owner of the minshuku across the road to use their bathroom for a small fee (about ¥300).
- At Mi-no-Koshi, there is limited camping available along the side of the trail to Mt Tsurugi (near the upper chair-lift station). Alternatively, ask nicely for permission to borrow a patch of lawn from one of minshukus — and show your gratitude by eating a meal or two there. Meoto-no-Ike (夫婦の池) is the nearest official campground, 2km up Route 438 toward Sadamitsu.
- Although there are no signs marking it as an official camping site, a tent can be discreetly pitched in the woods near the lake beside La Fôret Tsurugi's baths. It is also possible to use the herbal baths here (¥500).
There are a number of simple minshukus in West Iya and Mi-no-Koshi. The basic bed-only sudomari (素泊まり) rate starts at around ¥3500 per person, higher with dinner and/or breakfast.
- Hikkyo no Yu (秘境の湯), ☎ . A large and lavishly appointed onsen hotel right next to the tunnel entrance to West Iya...but it might as well be anywhere, there aren't really even any valley views. For non-guests, entry into the baths costs a steep ¥1000.
- Hotel Iya Onsen (ホテル 祖谷温泉), ☎ . About as far away from it all as you can get in Japan, located along a small ravine branching off from the west end of the valley and famous for the cable car that takes guests to the hot spring baths. But there's a price to pay: ¥14000 and up per head, to be precise.
- Hotel Kazurabashi (ホテルかずら橋), 32 Zentoku, Nishiiyayamason, Miyoshi-gun (15 min. by bus from Oboke station, 10 min. walk from Kazurabashi vinebridge), ☎ . A traditional ryokan with hot spring baths. Most guest rooms have mountain views, as does the open-air bath above the hotel (reached with a cable car). Dinner and breakfast are top-end kaiseki cuisine using local ingredients. ¥15,000 per person with meal.
- The gorges of Oboke and Koboke, with more scenic views and world-class rafting, are just outside West Iya.