Scuba-Diving Fishermen Filmed 'Walking' on Ice Under Water -- But How?

Its about that time of year where in wintry climates ice fishermen begin drilling holes in ice and setting up their huts above frozen lakes. The opposite is true for these underwater ice fishermen donning scuba gear in this mind-boggling video where they appear to be walking on ice underwater and attempting to fish from below.

Watch the film by Juuso Mettälä at lake Saarijärvi in Vaala, Finland:

Have you guessed how this worked? The scuba divers were actually filmed upside down walking on the surface ice underwater.

Many readers on Reddit were confused well into the film until the direction of the air bubbles started giving the secret away.