Way up in Slovakia's High Tatras Mountains is a lake that locals refer to as Velke Hincovo Pleso. Last year, 38-year-old hiker Tomas Nunuk and a friend went hiking through the area and recorded themselves walking on the surface of the lake, which had frozen over. While frozen lakes are hardly uncommon in the wintertime, particularly at higher elevations, it was the clarity of the ice that had everyone online talking.
The video, which was posted to YouTube on December 8, 2014 quickly racked up a staggering four million views in just a few short days. Many people commented that it was a fake since ice that clear tends to be thin and fragile enough to collapse under the weight of two adult men, while others simply didn't think lakes were capable of freezing without any cloudiness.
While these assertions are generally true in most cases, this ice was the result of some relatively rare but not impossible conditions. Cloudiness in the water is usually caused by either too much oxygenation at the time of freezing and/or snow in the water. When temperatures fall very quickly from being fairly mild to extremely cold and there's no snowfall, however, it is scientifically possible for the ice to freeze clearly. Accuweather reports of the area at the time confirm that this is indeed what the region experienced. Additionally, clear ice is actually twice as strong as cloudy/white ice and much more dense, so it can definitely hold up two adults.