Two different studies highlight very different elements of historical seafarers.
DNA taken from the tooth of a man who died in Alaska 10,300 years ago suggests that the earliest Americans travelled along the Pacific coast, possibly settling rapidly around 15,000 years ago. Modern indigenous American people were tested in comparison with the ancient remains, and only a small number had the mitochondrial DNA lineage of the ancient man. These individuals were all from indigenous groups that lived along the Pacific Coast of North and South America.
The idea that people migrated to the Americas by boat has become increasingly popular as older archaeological remains have made a land crossing over Beringia unlikely as the source for the first people in the hemisphere.
I will note that the research also found very fast rates of mitochondrial DNA mutation, the basis of the method. Four times faster, in fact. I'm a layman in regards to molecular studies, but that seems like something that needs more explanation.
The other story is much more recent, and much stranger. Viking sailors may have used crystals known as sunstones to help navigate even on cloudy days. The stones would allow one to see the polarization of sunlight and use that to determine the position of the sun for use in navigation. If this turns out to be the case, I hope someone goes and revises historical discussion of "magical" sunstones.