It's possible that Vikings during the 8th - 11th centuries, had the ability to navigate using a piece of Icelandic Spar called a Sunstone. The navigator would be able to find the sun even on cloudy days using refracted light and triangulation theories. In 2012 an excavation of a 16th century shipwreck revealed what is thought to be an actual sunstone. Even though this discovery was out of sync with the Vikings' timeline, it's close enough that the practice could have been handed down through generations, making the mystery of the Viking Sunstone closer to being revealed.
WHAT IS A SUNSTONE?
SunStone Technical Solutions (SunStone), is a non-populated Joint Venture formed by Solvere Technical Group (Solvere) and Valkyrie Enterprises. As approved participants in the SBA’s All Small Mentor-Protégé Program, Solvere, the Protégé, and Valkyrie the Mentor, formed the JV to provide customer focused and cost-effective solutions for our customers.