When Andrew Ballard shot this footage while fishing with his father on Lake Michigan, the looming fog bank could almost have been mistaken for an iceberg or the "wall" from "Game of Thrones."

In his stunning clip, the massive fog edges closer and closer until it nearly envelopes the small boat. Ballard told Storyful that he and his dad saw the fog in the distance and decided to stick around to check out the weather phenomenon — "advection fog" — up close.

Ballard told the Detroit News that the wind picked up to about 20 mph once they were inside the fog bank. "The waves got bigger and the temperature really dropped. Visibility dropped to about 30 feet, and you lost direction.”

Advection fog occurs when moist and warm air slides atop cold land or water, according to the Weather Channel. Meterologist Deb Elliott told the Detroit News the fog can be "very thick and extensive; if they were swallowed up in it, the ir visibility could drop to almost zero.”

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