The ice was almost completely transparent. Image Credit: YouTube / Tomas N
Tomas Nunuk and his friends stepped on to ice so clear that it was like walking on a sheet of glass.
The group had been hiking up the High Tatras mountain range in Slovakia when they came upon the frozen lake.
Nunuk took out his camera and started recording as he and his friends gingerly stepped out on to the glass-like surface.
The video shows him looking down at his feet which appear to be suspended in mid air above the rocks on the lakebed.
Since appearing on YouTube the video, which in entitled "Walking on beautiful clean ice in Slovakian Mountains", has managed to attract more than two million views.
Some users responded critically by accusing Nunuk of faking the video, however Slovak Igor Ludma maintains that it is possible for clear ice like this to form and for it to support the weight of a person.
"It is only possible when the temperatures fall from being relatively mild to very cold very quickly, and at the same time it's important that there has not been any snow which tends to make the ice very cloudy," he said. "And we have had those conditions lately which would explain this very clear ice."