Ōboke (大歩危) and Koboke (小歩危) mean, respectively, "big steps dangerous" and "small steps dangerous" — an apt description of the perils of traversing through these steep gorges on foot.
Rafting in the Yoshino River
It is recommended to travel in this area by car. If you get there by train, you'll have a long walk along a noisy road without sidewalks. It is also hard to find entry points for hiking trails without a car. Unfortunately, the nearest car rentals are located quite far away: Marugame, Takamatsu, and Tokushima.
National Highway 32 winds along the Yoshino River through the pristine valley. Coming from Osaka, Kobe or Tokushima, take the expressway and exit at Ikeda. Then follow route 32 towards Kochi for about 20 kilometers to Oboke.
A tunnel also connects Oboke to the western Iya Valley.
Both Oboke and Koboke have stations on the JR Dosan Line from Kochi to Takamatsu via Ikeda. Stops in Koboke are rare, though.
Buses to the Iya Valley from Oboke Station run almost hourly on weekends/holidays, less so during the week.
See & Do
There's one big reason to visit: the rapids rushing through the gorge below. There are observation platforms on the highway and near the train stations if you're content to gaze from a distance, but more daring types will venture down onto the Yoshino River for a sightseeing cruise (¥2000 for a one-hour loop), and more adventurous types yet will try their hand at white-water rafting in the class 4 rapids. The rapids are Japan's biggest and most exciting, with amazing rock formations and crystal clear waters.
- Happy Raft, ☎ +81 0887-75-0500, . Arranges half/full-day rafting trips from ¥5500/10000 (cash only), mostly July 1 to September 30. English spoken.
If you survive the experience without developing acute hydrophobia, both Oboke and Koboke have onsen hot springs offering more bubbling water to soak in.
- Boke-Mart is a normal grocery store, but probably the best place to stock up before heading into Iya Valley. It's near JR Oboke Station.
Ikeda is the closest town with a real supermarket.
Eat & Drink
The local specialties are ayu and amego, delicious river fish salted and barbecued on a stick.
Sleeping in the area is useful for exploring the Iya Valley and surrounding towns, but is a bit far of the eastern end of the valley. If looking for hiking opportunities, lodging closer to Mt Tsurugi might be a good idea.
- Happy Guest House, Iwahara Otoyo-cho Kochi (1 min walk from Tosa-Iwahara station), ☎ +81 0887-750-500, . Overlooking the Yoshino River, four different guesthouses are on offer set in traditional-style homes, each with private rooms and self-contained kitchens. Very friendly staff will pick you up and drop you off from the train station and drive you to your guesthouse. You will need to bring your own food as there are no shops nearby or meals served. The owners also run a rafting company but you don't need to book a rafting trip to stay at the guesthouse (but lodging discounts are given for those who go rafting). ¥2500.
- Ku-Nel-Asob (空音遊 Kūneruasobu), ☎ +81 090-9778-7133, . A hostel set in a traditional farmhouse in Oboke — the name means literally "eat, sleep and have fun". The owner is friendly and speaks great English. The communal vegetarian meals that are served are highly regarded. It's located within an old-style hillside community and is a little hard to reach if without a car, but the view down into the Oboke Gorge is lovely. Bathing is done at a nearby hotel (free rides given), which has outdoor baths (onsen) that overlook the river. Free pick-ups given from Oboke Station. ¥9000 including dinner.
- Momonga Village Guesthouse (モモンガビレッジゲストハウス), ☎ +81 0883-86-2334, . Located in a tranquil side valley up from the Yoshino River and central Yamashiro, this hostel-style guesthouse is quietly set aside from the busier river area. The traditional Japanese interior and tatami (futon) beds makes it a very local experience. International staff can help explain things and the place is connected with one of the rafting companies if you are looking to get your river thrills. Though a bit inconvenient if without your own car, the homely relaxed feel of the guesthouse more than makes up for the location, and the travel information and options for getting around make sightseeing around the main attractions very doable. They offer pick up services to a few different bus stops depending on where you want to go. Offering both dorms (¥2500) and private rooms (from ¥3600), dinner and/or breakfast is available by reservations and snacks and drinks can also be separately purchased. BBQ services are also available (expensive, around ¥2000). With bike rental (¥500) and car rental (from ¥5000/day). Free WiFi and free parking.
- Iya Valley, with more scenic views and some great hiking too, is just across the tunnel from Oboke.