How Japan Built the Seikan Tunnel Under the Sea — The Full Engineering Process

What does it really take to build a railway tunnel beneath the sea? In this video, we go inside Japan’s Seikan Tunnel, one of the most extraordinary engineering projects ever built. Connecting Honshu and Hokkaido, the tunnel runs deep beneath the Tsugaru Strait and was constructed under some of the most challenging conditions imaginable. From underwater geological surveys and massive excavation machines to drilling, blasting, rock reinforcement, waterproofing, ventilation, drainage, and railway installation, discover the complete process behind building this enormous undersea railway tunnel. You’ll see how engineers dealt with unstable rock, extreme water pressure, flooding risks, and the immense technical challenges of constructing a railway passage beneath the ocean. 🚆 Inside the Seikan Tunnel 🌊 Undersea construction ⛏️ Excavation & drilling 🏗️ Engineering & construction process 🇯🇵 Japan’s incredible infrastructure Watch until the end to understand how one of the world’s most ambitious underground railway projects became a reality. Subscribe for more incredible engineering, megaprojects, infrastructure, and construction documentaries.