Another important navigational technique used by the Vikings was latitude sailing.
Since the coastline of Norway runs basically north-south, experienced sailors knew that if one sailed north or south to a particular point on the Norwegian coast, then struck due west from that point, then the ship would always arrive at its destination if it maintained the straight westerly course.
For instance, Sturla Þórþarson in his version of Landnámabók (c. 1275) states that in order to reach Hvarf, Greenland one would first sail to Bergen, Norway, then sail due west, and in time the ship would arrive very near to Hvarf.
Using the sextant device described above would facilitate this procedure, since all one would need to do is mark the altitude of the noon sun before leaving Norway.
Each subsequent day at noon the distance between the sun and the horizon would be measured again. If the altitude was greater than the starting mark, the ship had sailed too far to the south; if the height was less than the mark, the ship had wandered north of the proper course. With this information, the navigator could correct his course until the sun-height measurement was back to the original mark.

While the Vikings could not measure longitude, they used time as a measurement of distance, knowing that a certain number of "days' sailing" would bring their ship to port.

In addition to the Sun, the Viking seaman also relied upon the Pole Star to show him true North when the midnight sun of the arctic did not obscure the stars, and his use of astronomical data extended to a very sophisticated understanding that the tides were caused by the moon and varied with His waxing and waning (remember, to the Vikings Sunna the Sun is female, while Mani the Moon is male).

Like other medieval sailors, the Vikings also relied heavily upon empirical experience gained from their predecessors and from their own voyages.
In many places, the Baltic and North Seas are shallow enough to be sounded for depth using a lead weight attached to a line. Increasing shallowness of the ocean floor indicated that the ship was nearing land, and it was oftentimes useful to attach wax to the weight in order to sample the seabed, for the color and nature of the sand or mud could also act as a kind of "landmark" to indicate to the experienced seaman his whereabouts. Observation of birds or of whales could also provide important clues that land was near: Floki Vilgertharson used consecrated ravens released from his ship (much like a latter-day Noah with his doves) in order to locate Iceland, and Landnamabok notes that the presence of birds and whales marks the southern edge of Iceland.

Another important clue for the navigator were the low-lying fog or cloud-banks indicating land on the horizon, for the westward path outbound from Norway passes the Shetlands, the Orkneys, the Faroes, Iceland and Greenland, and each of these served as signposts for the sailor passing them westward bound.