Imagine walking 750 meters into a mountain — and coming out somewhere that feels like a dream. Kiyotsu Gorge, Niigata. “Tunnel of Light,” designed by architect Ma Yansong. You walk through a corridor that glows — color washing over the walls, soft and shifting, the air cool and bright. Then the last chamber opens. A thin sheet of spring water covers the polished floor, and suddenly the whole world doubles. Towering columnar cliffs and an emerald river fold down into a perfect mirror at your feet. Visitors wade in slowly, shoes off, gasping the moment the water meets the sky. A Japanese family steps in laughing. Children crouch to touch their own reflection. An American family wades alongside them, everyone grinning, becoming bright little silhouettes inside the view. Entry: about eight dollars. It was once just an old sightseeing tunnel in a quiet mountain town — rebuilt into pure wonder. You stand in the mirror. Cliffs frame the sky. The water glows green and gold. And for one perfect second, everyone is smiling at the same impossible view.