Two hikers went for a wintery walk in the Tatra Mountains in Slovakia. There, they stumbled upon an amazing discovery: a lake that had frozen over with such pristine and crystal-clear ice, that you can barely tell it’s there. It’s quite rare, and scientists says that it’s because it froze at a very slow rate, allowing bubbles and impurities to escape. There was probably no wind at the time either.

Check out the video below:

This video is just a tiny glimpse into the wonders of Slovakia, and all the surprises that might await you.