How did the Vikings navigate when land was out of sight? Most likely they learned intuitive navigation and how to use nature as a guide. This kind of knowledge was passed down from generation to generation, just like the stories from the Norse sagas.
We cannot determine if the Vikings used any kind of navigation instruments to find their way. But, it is likely that they had a sun compass. On foggy days the “sunstone”, a piece of mineral that polarizes light and tells the position of the sun, would be of great help. When the night sky was clear they used the stars. By looking at birds and the color of the sea, they could tell if land was close.