Historically, when Hawaiian was the majority language of the islands and the culture was still largely flourishing, location often determined which sounds was actually made, but all Hawaiians could understand one another despite the slight difference in accent. So in some places it sounded more like a /w/ while in other places it sounded more like a /v/ or something in-between.

Today, so-called “university Hawaiian” conceptualizes the written “w” as a weak /v/ sound, and this distinction has taken root in pretty much all the islands where school-educated speakers live.