15 DEEPEST Tunnel Networks
Fifteen stories down, the world flips upside down. Beneath our cities, oceans, and mountain ranges, engineers have carved out vast tunnel networks so deep they might as well be secret worlds—where daylight never reaches, temperatures soar or freeze, and a single mistake could flood, crush, or strand everything inside. In this video, we’re diving into the 15 deepest tunnel networks ever built, and the extreme risks, wild engineering, and hidden purposes buried far below the surface. Credit to: Top Fives
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