The Sixty-Sixth Parallel is a circle of latitude located 66.5 degrees north of the equator. It is significant because it marks the boundary of the Arctic region, where the sun does not set during the summer solstice and does not rise during the winter solstice. This phenomenon is known as the Midnight Sun and Polar Night, respectively. This parallel passes through several countries, including parts of Norway, Sweden, Finland, Russia, Alaska in the United States, and Canada. The area north of this parallel is characterized by extreme weather conditions, unique ecosystems, and diverse wildlife, including species like polar bears and arctic foxes.