I learned to navigate using the sextant, chronometer, magnetic compass, and navigational charts, but the Vikings did not have access to any of these.

In those days, most sailing was coastal, in which the ships were always within sight of land. Yet to reach the British Isles, and later Iceland and beyond, these intrepid sailors had to brave the open sea for longer periods of time. Setting out from the west coast of Norway, the next landfall was a two or three night passage. To the west of Norway lay three groupings of very small islands: the Orkneys, the Shetlands, and the Faroes. If a ship missed these islands there’s nothing out there but open sea for days on end, sailing until they ran out of water and food. The Norse name for this was hafvilla, lost on a vast expanse of sea.

The Vikings used a form of navigation known as latitude sailing, mentioned in some of the old sources, such as the Landnamabok and the Greenland Saga.

The Norse called Polaris leiðarstjarna, leading star. It is the one star that is always in the north. From Norway’s west coast, Norse navigators measured the height of the North Star above the horizon at specific departure places, from which they could sail due west to a destination of the same latitude. For instance, Bergen, Norway is due east of the Shetland Islands.

As their journey continued, the Norse sailors could tell how far north or south they were from their starting point by measuring the North Star’s height above the horizon relative to the star’s height at their departure point.

In the northern latitudes in summer the sky doesn’t get dark enough to use star navigation, so sighting the sunrise and sunset was vital. However, the horizon is not always clear, due to fog or cloud cover.

Several Icelandic sagas describe a sunstone, a mysterious mineral that enabled the navigator to see the sun even through fog and clouds. It is possible that the sunstone was a crystal, possibly the Icelandic Spar.

Though the Vikings did not have a magnetic compass, they divided the horizon into eight directions: North, East, South, and West were primary. Northeast was referred to Land North and southeast Land South, since east was the direction their homeland lay. Northwest was Out North (outbound) and Southwest was Out South.

There is some evidence that the Norse navigators may have used a disc with notches carved in the edge to take bearings or track the sun’s shadow. A find in Greenland of half a notched disc may be the remains of such an instrument.

The Vikings also used signs in nature, such as the behavior of birds, the direction of the ocean swell, cloud formations to determine their proximity to land. According to the early Icelandic Landnámabok, one of the first Norsemen to settle in Iceland was nicknamed Raven-Floki because he used ravens as a navigation aid. Floki released the birds while he was at sea, knowing they would lead him to land.

Our knowledge of Viking Age navigation is scant, based on vague references in sagas and archeological finds. One thing  is certain, these intrepid voyagers were skilled and courageous explorers.