Two Slovak climbers during their little expedition to High Tatras Mountains in Slovakia came to a lake. What they found there is a completely frozen and transparent lake. As you can check in the video they have been walking over the lake and it looks like they are levitating. The news of this soon vent viral over Reddit where some that are more into the topic explained that clear ice has very little to do with currents and much more to do with the rate of freezing. Meaning that if the water is cooled too quickly it doesn’t have enough time to reject any impurities as it crystallizes – those impurities are then held within the crystal lattice and distort the crystal lattice thus making the frozen lake look transparent.