People, beware! If you see something like this coming your way when you?re out in the water, head back immediately to shore.

The video was shot by Andrew Ballard and his father in Lake Michigan, all of a sudden they saw an enormous wall of fog moving towards them.

The mistake? They stayed there and the fog swallowed the blue sky and the lake.

According to meteorologist Deb Elliot ?Fog develops as the air is cooled and is then moved along by wind. It can very thick and extensive; if they were swallowed up in it, their visibility could drop to almost zero.? Elliot told The Detroit News.

Andrew and his dad got lost in the fog, they say inside it is not calm at all, with strong winds and cold temperatures.

They made it out using their GPS to go back to shore.