Drone footage captured a rare and mesmerizing “square wave” phenomenon on Lake Michigan near Michigan City, Indiana, on January 13. These visually striking waves form a grid-like pattern on the water's surface, a result of two separate wave swells intersecting at an angle. This creates a crisscross effect known as a cross sea. While appearing unusual and even dangerous, square waves are a natural occurrence that arises from the meeting of waves traveling in different directions.