The 66th parallel north is a circle of latitude that is 66 degrees north of the Earth's equatorial plane, about south of the Arctic Circle. It crosses the Atlantic Ocean, Europe, Asia and North America.
This latitude also roughly corresponds to the minimum latitude in which midnight sun can last all night near the summer solstice.
At this latitude midnight sun lasts from about 12 to 29 June, and the sun is visible for 2 hours, 47 minutes during the winter solstice. At midnight on the summer solstice, the altitude of the sun is 0.00°.
Starting at the Prime Meridian and heading eastwards, the parallel 66° north passes through: