How Japan Built an Impossible Bullet Train Tunnel Under the Ocean (Full Process)

🌊 In 1954 a typhoon sank five ferries in one night — killing 1,430 people in the Tsugaru Strait. Japan's response took 34 years, $7 billion, and 2,900 tonnes of explosives detonated 240 meters beneath the ocean floor. ⚙️ How do you drill 53km through unpredictable volcanic rock without a single tunnel boring machine? 💧 How do you survive when water bursts through the tunnel face at 80 tonnes per minute? 🚄 And why does the bullet train have to slow down inside the world's most expensive tunnel? This is the full construction story of the Seikan Tunnel — the deepest, most dangerous underwater railway ever built. #Japan #SeiканTunnel #MegaProject #Engineering #Overbuilt #Infrastructure #Documentary #HowItWasBuilt