Leif Erikson was arguably the most famous Viking of all time.
He was a Nordic explorer from Norway, who discovered Greenland. He lived from roughly 970-1020 AD, and landed in America sometime in 1000, 492 years before 1492 when "Columbus sailed the ocean blue."
Navigation was not an easy task for Erikson because the Nordics sailed at such northern latitudes that the summer sky was too bright at night, disallowing the use of stars for navigation.
The Vikings used a clever method to remain on course: Calcite sunstones! Calcite is a type of crystalized mineral that refracts two visible wavelengths of light, which, when paired with a bearing-board allowed for very accurate latitudinal navigation!
The Vikings used this method very well, but Erikson's landing in North America, which he named Vinland, was still an accident, so it obviously wasn't a perfect method!
