Subterranean flood water diversion channel with towering concrete columns and dramatic lighting.
Inside the impressive Subterranean Flood Water Diversion Channel, showcasing towering concrete columns and dramatic lighting.

G-Cans : Japan’s Underground Temple

Hidden below the Tokyo streets is a true superhero – a bitumen-washed facility with state-of-the-art technology and an architectural beauty to put a Corbusier or two in the shade. This is G-Cans, also known by the unlikely name of Metropolitan Area Outer Underground Discharge Channel.

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But it’s not just a pretty face! It’s an underground water storage tank, part of a titanic floodwater diversion facility. This is the biggest reservoir, but it’s not the only one. It’s the culmination of a series of five huge silos with a connecting tunnel extending over 6 kilometres.

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I’ll try to explain the system simply for anybody interested. The outskirts of Tokyo to the north are criss-crossed with rivers and streams. In times of heavy rainfall, this densely urbanized zone has always been subject to extensive flooding, very costly to deal with. A solution had to be found, and this is it.

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Beyond this last reservoir is the Edo River. On the other side are the silos – interconnected of course. These absorb floodwater from the other rivers in the surrounding area and gradually feed it down through the tunnel to the storage tank where we stand.

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The water flows relatively slowly towards this reservoir, to be stored then gradually pumped into the Edo River by 14,000-horsepower turbines.

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In fact the facility is only in use between June and November, roughly between the rainy and the typhoon season.

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The rest of the time, the site is open to the public and entry is even free. But there’s no denying access is difficult from Tokyo and there’s little else to visit nearby.

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By the way, after you’ve seen the exhibition and video, the actual tour is extremely short. You’re only allowed to explore the inside of the storage tank for ten minutes.

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All the photos posted here were taken in that time. Best be prepared! 🙂

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And this is the only entrance (and exit) to the “Underground Temple”. Imagine all that really lies beneath our feet, especially in the big cities …

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For security reasons, visitors must speak Japanese or be accompanied by someone who does. You also need to book well in advance via the official website. For more information visit the G-Cans English page.

If you like impressive, extraordinary structures, have a look at my articles on  Gunkanjima, of course,  the awesome Super-Kamiokande, as well as that strange Tokyo building, the Nakagin Capsule Tower.

And for more awesome content about Japan, follow Jordy Meow on Instagram ! 🎵

Who Am I

Jordy Meow
This is me!

I am Jordy Meow, a French photographer based in Tokyo. I explore offbeat places in Japan.

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Emerald embrace, In the circle of bygone— Nature's quiet reign.  エメラルドの抱擁、 過ぎ去りし円の中で— 自然が静かに統治する。  #haikyo #urbexjapan #offbeatjapan #forgottenplaces #ancientvibes #naturetakeover #japan
Dusky bottles sigh In the silence of lost time, Light whispers secrets. 光が囁く、 失われた時の中、 くすんだ瓶のため息。 #offbeatjapan #japan #haikyo #urbexjapan #hiddenhistories #forgottenplaces #mysteriouslight #vintagevibes
Winding path of dreams, Terracotta whispers soft, Lanterns guide the heart. 夢の小道、 素焼きの囁き、 灯籠が心を導く。 #offbeatjapan #japan #historicvillage #traditionaltown #serenesettings #culturalheritage #lanternlight
Emerald circle, Teal whispers 'round stories told— History afloat. エメラルドの輪、 話を語る青の囁き、 歴史が浮かぶ。 #offbeatjapan #japan #mysticalisland #naturelovers #hiddenjapan #historicaltreasures #uniquepaths
A magical night at an abandoned onsen, where milky blue waters blend with glowing lights in a peaceful forest. Tradition and nature meet in this perfect spot for relaxation and serenity.幻想的な夜、廃墟の温泉で。乳白色の水と光が森の中で静かに調和しています。伝統と自然が融合し、リラックスと穏やかさがここにあります。#onsen #japantravel #serenescape #traditionmeetsnature #abandonedplaces #offbeatjapan #japan
A captivating night scene in Japan where ancient traditions meet modern city lights. This balance of the old and new is what makes urban life here so unique and beautiful. 静かな夜、日本の都市で古と現代の光が交わる情景。この古と新の調和が、ここ日本の都市の魅力を引き立てます。 #UrbanJapaneseNights #TraditionMeetsModern #NeonAndLanterns #TokyoVibes #CulturalContrast #OffbeatJapan #Japan
From the weathered castle roof, witness the timeless beauty of Japan as a quaint town rests peacefully amid rolling hills and a golden sky. 🌄🏯---古びた城の屋根から、静かに横たわる谷の町と黄金の空を背景に見渡す日本の時を超えた美しさ。🌄🏯---#offbeatjapan #japan #castleviews #historicjapan #sunsetmagic #explorehistory #tranquility
A pop of color brightens the roadside with this charming fruit-shaped bus stop, showcasing Naoshima's unique blend of art and practicality, where every corner holds a piece of its creative spirit.カラフルなフルーツ型のバス停が道端を彩ります。直島では、アートと実用性が見事に融合し、創造的なスピリットがあちこちに漂っています。#Naoshima #offbeatjapan #artisland #creativebusstop #uniquearchitecture #tangerinedream #japan