Yes the Vikings were the first to navigate in the ocean away from the site of land. That is what made them dangerous because you could not spot them coming until they came over the horizon to attack.
They made it to many lands and explored a lot of the earth that we did not know about. There are signs that they made it to the new world in the 9th or 10th century even in land as far as Minnesota and Iowa from following the great lakes.
I think the Vikings were responsible for some the advances in war fare as communities started to build walls to protect themselves from the Vikings.