In Scandinavia the custom was that eldest son in the family inherited the farm. This meant that there were a lot of people which had to choose between being workers on their brothers farm or going abroad in search of fame and fortune. The rumours about how easy it was to get rich on such expeditions spread like wild fire over the Scandinavian peninsula.
In Scandinavia there were not yet any uniform states; Sweden, Denmark and Norway didn't exist. All the Nordic people spoke the same language and the differences between the people waere not as great as they are today. Everyone had the same religion where the proud and brave warrior had a central place. Cowards went to Hel's kingdom of the dead, and the ones who died a brave death in combat went to Paradise (Valhall) where they could drink mead, fight and hunt women all day long.
Quite naturally, the Vikings who lived on the coast of Norway mostly went westward to the British Isles, Ireland, the Faroe Islands, Shetland, Orkney and the Hebrides. England was called Bretland. From Norway it is about 350 kilometers to Shetland and from there you can see the next island, Orkney, and so on.