hi! There's always room for more discussion here, but fyi, there have been a few threads on Polynesian travel/navigation and trade. Check these out

• What kind of contact did the polynesians have with each other and the rest of the world? - featuring /u/b1uepenguin

• How would the Polynesians have been able to discover an island like Easter Island that is near 1,000 miles away from the nearest island? - a post of links; see the last section in particular

and, in case you're interested, a couple of recent comments on the possibility of Polynesian contact with South America

• Did Polynesians ever make contact with other groups of people before modern times? Particularly in North or South America? - featuring /u/gargatua13013

• The wikipedia article about pre-columbian contact of "old world" civilizations with American natives lists a number of possible instances. Which ones are the most accepted? - featuring /u/reedstilt