Sun and Stars
Vikings didn't have maps therefore they needed to travel the seas using special techniques. Vikings had many different ways of helping them find out where they were and the direction they were traveling, most of the time the vikings used the suns position to help them, if it was dark they would use the moon and the stares, there was one stare that the vikings used called the Polaris which would help them figure out where their north and south was, centers later the same stare was being used to help explores find their way.