The mine tunnels of Smolník, Slovakia, form an impressive underground network dating back to medieval times, with shafts and galleries stretching up to 3 kilometers long and reaching depths of around 360 meters. One of the most fascinating features is the Maria Theresa Water Tunnel, a nearly 2-kilometer hand-dug canal built between 1768 and 1794 to power mining operations—its misalignment at the meeting point of the two digging teams remains visible to this day. At its peak, Smolník used over 300 troughs to extract copper through an innovative cementation process, producing thousands of centners of pure copper annually. Although mining ceased in 1989, the tunnels stand as a remarkable example of historical mining ingenuity and engineering. We stopped at one of the many openings and hid a penguin stone here. 

Last known location –  48.7348707N, 20.7506248E

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