Shimanto River: Japan’s Last Clear Stream, Submersible Bridges & Ancient Fishing by Firelight

The Shimanto River is where nature remains untamed — no dams block its flow, no railings line its bridges, and fishermen still hunt with torches on moonless nights

Why the Shimanto Is Called “Japan’s Last Clear Stream”

At 196 kilometers, the Shimanto River is the longest river in Shikoku. But length alone isn’t what draws visitors here. The Shimanto earned its legendary title — “Japan’s Last Clear Stream” (日本最後の清流) — because its main channel has never been blocked by a large-scale dam.

No massive concrete walls. No industrial reservoirs. The river flows as it has for centuries, carving a reverse S-shape through western Kochi Prefecture before emptying into the Pacific Ocean. The banks remain free of concrete embankments, and the surrounding landscape of forested mountains and rice paddies has barely changed in generations.

NHK first popularized this nickname in a 1983 documentary, and the designation stuck. In 1994, the river’s official legal name was changed from “Watari River” (渡川) to “Shimanto River” — the first time in Japanese history that a major river was officially renamed under the River Act. The name “Shimanto” itself may derive from an Ainu word meaning “extraordinarily beautiful,” though scholars continue to debate its true origin.

The Shimanto is also one of Japan’s Three Great Clear Streams (alongside the Nagara River and Kakita River), a designated Top 100 Water Source, and one of Japan’s 100 Secret Places. Its entire watershed has been recognized as a Cultural Landscape by the Ministry of Education — not just for scenic beauty, but for the centuries-long harmony between people and nature along its banks.

A River Without Dams — Almost

The “no dam” claim requires a small asterisk. A structure called the Iejigawa Weir (家地川堰堤) does exist on the main channel. Built in 1937 for wartime hydroelectric power, it diverts nearly half the river’s water to a power station in a completely different river system — the water never returns to the Shimanto. However, because Japanese law defines a “dam” as a structure taller than 15 meters, and this weir stands at just 8 meters, the Shimanto technically remains “dam-free.”

Ironically, the weir may actually help maintain the river’s famous clarity. Upstream of the weir, the town of Kubokawa’s wastewater enters the river. By diverting that water away, the weir prevents most pollutants from reaching the pristine downstream stretches that tourists visit. Below the weir, dozens of crystal-clear tributaries gradually restore the Shimanto to its full, magnificent flow.

Submersible Bridges: Walking on Water

The most iconic feature of the Shimanto River isn’t the water itself — it’s the submersible bridges (chinkabashi, 沈下橋) that cross it. These low-slung concrete bridges have no railings whatsoever. When typhoons send the river surging, the bridges disappear entirely beneath the surface — by design.

The logic is elegant: without railings or tall structures, floodwater and debris pass over the bridges instead of smashing into them. The bridges survive by surrendering to the river rather than fighting it. This philosophy — coexisting with nature rather than controlling it — defines the entire Shimanto culture.

The Shimanto River system has 47 to 48 submersible bridges across the main channel and tributaries. Kochi Prefecture designated them as Living Cultural Heritage for preservation in 1993. The oldest surviving bridge, Ittohyō, dates to 1935.

Sada Submersible Bridge (佐田沈下橋)

The most accessible and most visited bridge. Located furthest downstream at 291.6 meters long — the longest on the Shimanto — Sada Bridge sits just 15 minutes by car from Nakamura Station. The surrounding area blooms with canola flowers in spring, adding yellow carpets to the already photogenic scene. During peak tourist season, local authorities ask visitors to cross on foot rather than by car to avoid congestion.

Iwama Submersible Bridge (岩間沈下橋)

The most photographed bridge on the river. Iwama Bridge (120 meters long, 3.5 meters wide) sits at a dramatic S-curve where the emerald river bends between forested mountains. This is the bridge that appears on virtually every Shimanto River poster, travel brochure, and TV program. Built in 1966, it was closed for several years after 2017 but reopened in 2021. Cars can cross, but the narrow width makes it a one-at-a-time affair.

Katsuma Submersible Bridge (勝間沈下橋)

Famous as a filming location for the popular movie series Tsuri Baka Nisshi (“Fishing Fool’s Diary”). At 171.4 meters long, Katsuma Bridge is distinctive for its three-legged steel pipe pillars — the only bridge on the Shimanto main channel with this design. It’s also one of the best spots for that classic “bridge disappearing into the distance” photograph.

Takase Submersible Bridge (高瀬沈下橋)

The third-longest bridge on the river, surrounded by particularly serene countryside. Takase is known for summer firefly viewing and riverside camping. The atmosphere here feels more remote and less touristic than Sada or Iwama, making it ideal for travelers seeking solitude.

Kuchiyonai Submersible Bridge (口屋内沈下橋)

At 241.3 meters, this is one of the longest bridges but is closed to vehicles — pedestrians only. The nearby Kurosongawa tributary valley is spectacular during autumn foliage season (early to late November), making this bridge a destination for hikers and photographers alike.

Things to Do on the Shimanto River

Kayaking and Canoeing

Paddling is the definitive Shimanto experience. The river’s gentle current makes it accessible to complete beginners, while the scenery — passing beneath submersible bridges, gliding past untouched forest — is extraordinary for everyone.

Four main operators serve the river:

Operator	Location	Short Experience	Half-Day Tour
Canoe-kan (カヌー館)	Midstream (near Ekawasaki Station)	Available	Available
Kawarakko (かわらっこ)	Downstream (near Nakamura)	¥6,000/person	¥9,500/tandem
withRIVER	Downstream (near Nakamura)	Available	Available
Shimanto Base	Midstream	Private group	Available

All operators provide kayaks, paddles, helmets, and life jackets. Just bring clothes you don’t mind getting wet. Reservations are essential. The “experience” option means playing at one spot on the river, while “touring” means paddling downstream — typically about 3 to 3.5 kilometers of pure river immersion. Some operators also offer SUP (stand-up paddleboarding), snorkeling, and combination packages. Kawarakko even allows dogs on tandem kayaks if you bring your own pet life jacket.

Sightseeing Boats (Yakatabune)

For those who prefer to sit back and absorb the scenery, traditional yakatabune (roofed sightseeing boats) cruise the river year-round. Shimanto no Ao (四万十の碧) is the most popular operator, running wheelchair-accessible boats through a route that passes beneath two submersible bridges featured in TV dramas. The boats follow the river’s dramatic S-curves through areas where no houses or roads are visible — just water, forest, and sky.

Advance reservations are strongly recommended. The tourism association at Nakamura Station sells tickets at a 10% discount. Yakatabune Sakoya (さこや) departs from the east end of Sada Submersible Bridge, offering a more intimate experience with the river’s most famous crossing.

Cycling the Submersible Bridges

Rental bicycles are available from Canoe-kan and Nakamura Station. The ride from Nakamura to Sada Submersible Bridge takes about 40 minutes, and from there you can continue upstream to visit multiple bridges in a single day. The flat riverside roads make this an enjoyable ride for most fitness levels, and crossing a submersible bridge by bicycle — with the river rushing beneath your wheels and nothing between you and the water — is unforgettable.

Shimanto Trolley Train (しまんトロッコ)

The Yodo Line (予土線) runs along the Shimanto River between Kubokawa and Uwajima stations, and its star attraction is the Shimanto Trolley — Japan’s very first trolley sightseeing train, introduced in 1984 as a converted freight car. The current version, redesigned by famous train designer Eiji Mitooka, features a bright yellow body that stands out against the green valley.

The open-air trolley car operates between Ekawasaki Station and Tosa-Taishō Station (about 50 minutes), crossing the river on iron bridges and threading through tunnels while the Shimanto winds below. Volunteer guides narrate the journey, and local snacks are sold onboard. The seat reservation costs ¥530 for adults and ¥260 for children (plus regular fare), and is available one month in advance at JR Midori-no-Madoguchi windows. The trolley runs on weekends and holidays from April to May and July to November, with daily service during August.

The Yodo Line also runs two other novelty trains — the Kaiyo-do Hobby Train (decorated with kappa water-spirit figurines by the world-famous figure maker) and the Railway Hobby Train (modeled after the Shinkansen 0-series). Together they’re affectionately known as the “Yodo Line Three Brothers.”

Ancient Fishing Traditions Still Alive

The Shimanto isn’t just beautiful — it’s still a working river. Professional river fishermen (kawa ryōshi) continue to earn their living from the Shimanto using techniques passed down for generations. In an age of industrial fishing, this is extraordinarily rare.

Hiburi-ryō: Torch-Lit Ayu Fishing (火振り漁)

The most dramatic tradition. On moonless summer nights, fishermen set nets across the river, then stand in small wooden boats swinging blazing torches over the water. The terrified ayu (sweetfish) flee from the firelight — straight into the waiting nets.

Watching from the riverbank as torch flames dance across the dark water, their reflections shimmering on the surface, is one of Shikoku’s most atmospheric experiences. The tradition is so deeply embedded in local culture that a popular local chestnut shōchū spirit is named “Dabada Hiburi” after the technique.

Fire-fishing season runs from July to October. Only licensed fishermen with special permits can perform the actual fishing. However, organized experience tours allow you to ride in a river boat during the torchlit fishing, help remove ayu from the nets, and eat salt-grilled freshly caught ayu on the riverbank afterward. Tours run on Saturday evenings (18:30 to 21:30) and cost ¥8,500 for adults. Note that tours are cancelled during and after heavy rain — the river needs 4 to 5 days to return to normal after storms.

Shibazuke-ryō: Branch-Trap Fishing (柴漬け漁)

A quieter but equally fascinating technique. Fishermen bundle branches of chinquapin or yamamomo trees and submerge them on the riverbed for days. Eels, river shrimp, and crabs take shelter in the dark tangles. When the fishermen return, they lift the bundles over large scoop nets and shake the catch free. This method has been used on the Shimanto since at least the Edo period. Tourist-friendly shibazuke fishing experiences are available through local operators.

Other Traditional Methods

The Shimanto supports an extraordinary diversity of fishing techniques that have disappeared from most other Japanese rivers. These include toami (cast-net fishing for ayu), korobashi (cylindrical bamboo traps baited with earthworms for eels), ayu tomozuri (friend-fishing, where a live decoy ayu lures territorial wild ayu onto hooks), and ishiguro (stone pile traps that create artificial eel habitats on the riverbed). Seeing these ancient methods in action is a reminder that the Shimanto River isn’t a museum exhibit — it’s a living ecosystem where human traditions and natural rhythms still move in sync.

Shimanto River Food: Eating the Clear Stream

The Shimanto’s food culture is inseparable from the river itself. Every signature dish comes straight from the water flowing past.

Tennen Ayu (天然鮎) — Wild Sweetfish

The undisputed king of Shimanto cuisine. Wild ayu — called kōgyo (“fragrant fish”) for their distinctive cucumber-like aroma — are nothing like farmed versions. Salt-grilled over charcoal until the skin crisps and the flesh stays moist, they represent summer on the Shimanto. Season runs from June to October, with peak flavor in midsummer. The Shimanto was historically Japan’s top ayu-producing river, though catches have declined significantly since the 1990s, making wild-caught ayu an increasingly precious experience.

Tennen Unagi (天然うなぎ) — Wild Eel

Shimanto wild eel is a premium delicacy that commands extraordinary prices. Unlike farmed eel, wild Shimanto eel has firm, muscular flesh with a clean, non-greasy flavor — a result of the sandy riverbed (no muddy taste) and the rich natural diet of river crab, shrimp, and small fish. Expect to pay ¥3,500 to ¥7,000 for a wild eel bowl, compared to around ¥2,000 for farmed. The fishing season runs from April to September, caught using korobashi traps and other traditional methods. Outside this period, restaurants serve frozen wild eel.

Shimantoya (四万十屋) is the most famous restaurant for wild eel, perched directly on the Shimanto River bank with terrace seating overlooking the water. They’ve been serving river cuisine since 1967. Reservations aren’t accepted — arrive early, especially on weekends. Their menu also features river shrimp, aonori tempura, and gori tsukudani.

Kawaebi (川エビ) — River Shrimp

Tenaga-ebi (long-armed shrimp) deep-fried until crunchy is the quintessential Shimanto snack. The entire shrimp is edible — shell, legs, and all — with a satisfying crunch and delicate sweetness. Available at riverside restaurants and at roadside stalls at the Michi-no-Eki Yotte Nishi-Tosa rest stop, where they’re grilled fresh alongside ayu.

More Shimanto Flavors

Aonori (青さ海苔) is the river’s signature seaweed, harvested from the brackish water near the estuary and fried as intensely fragrant tempura. Gori (ゴリ) — tiny gobies — are simmered into rich tsukudani. Tsugani (ツガニ), the local freshwater crab, appears in autumn (August to October) and is prized for its rich, briny flavor. And Shimanto bushukan (四万十ぶしゅかん), a local citrus unique to the region, adds its distinctive fragrant acidity to fish dishes throughout autumn.

Nearby Attractions

Nakamura: Tosa’s Little Kyoto

The town of Nakamura (now part of Shimanto City) serves as the gateway to the river and holds its own historical fascination. In 1468, the former Imperial Regent Ichijō Norifusa fled the devastating Ōnin War in Kyoto and established a miniature capital here, deliberately modeling the street layout on Kyoto’s grid pattern. Although earthquakes, floods, and fires have destroyed most original buildings, the grid-pattern streets and Kyoto-derived place names — Gion, Kyōmachi, Kamogawa, Higashiyama — survive as echoes of that transplanted aristocratic culture. Nakamura even holds a Daimonji Okuribi fire festival on hilltops, mirroring Kyoto’s famous summer tradition. It was instrumental in founding the national Little Kyoto association in 1985.

Yasunami Suisha no Sato (安並水車の里)

A row of over a dozen wooden water wheels turning slowly along an irrigation canal, set against a backdrop of rice paddies and mountains. The canal was originally built in the Edo period by Nonaka Kenzan, a powerful retainer of the Tosa Domain’s ruling Yamauchi clan. The water wheels are now maintained for tourism, and the scene is at its most beautiful in late May to early June when hydrangeas bloom along the waterway. Located just 10 minutes by car from Nakamura Station.

Michi-no-Eki Yotte Nishi-Tosa (道の駅よって西土佐)

A roadside rest station in the Shimanto midstream area where you can sample river foods at their freshest — grilled ayu, fried river shrimp, and seasonal specials. The attached market sells local produce, river fish products, and Shimanto souvenirs. It also serves as a pickup point for bento boxes ordered for the Shimanto Trolley train ride.

Shimanto City Museum (四万十市郷土博物館)

Located in Tamematsu Park overlooking the town, this museum chronicles the history and culture of life along the Shimanto River. The park itself occupies the ruins of a Sengoku-period castle and serves as a popular cherry blossom viewing spot in spring.

How to Get to Shimanto River

From Major Cities to Nakamura Station

From	Route	Time
Kochi City	JR Limited Express “Shimanto” to Nakamura	~1 hr 40 min
Kochi City	By car via expressway	~2 hours
Matsuyama	JR to Uwajima, then Yodo Line to Ekawasaki/Kubokawa	~4-5 hours
Osaka	Flight to Kochi + JR to Nakamura	~3.5 hours total

Getting Around the River Area

Rental car is strongly recommended. The submersible bridges are spread along a 40+ kilometer stretch of river, and public transport options between them are extremely limited. Nakamura has several car rental agencies near the station.

Without a car, the Shimanto Trolley Bus (しまんとトロリーバス) runs a limited sightseeing route from Nakamura that includes Sada Submersible Bridge, but won’t reach the more remote upstream bridges. For the midstream area (Canoe-kan, Ekawasaki), the Yodo Line provides rail access, though services are infrequent — check timetables carefully.

Shimanto River Visitor Information

Item	Details
Best Season	May – November (summer for ayu & activities; autumn for foliage)
Ayu Season	June – October
Wild Eel Season	April – September
Fire Fishing	July – October (Saturday evenings)
Trolley Train	April-May & July-November (weekends/holidays)
Tourist Info	Shimanto City Tourism Association, Nakamura Station (0880-35-4171)
Transport	Rental car essential for full exploration

Nearby Kochi Attractions

• Hirome Market, Kochi — 2 hours drive
• Cape Muroto — 4 hours drive (opposite coast)
• Cape Ashizuri — 1 hour drive south
• Niyodo River — 2.5 hours drive

Part of our Kochi Prefecture Guide — exploring Japan’s wildest prefecture