Back to Ni'ihau
When the Hawaiian language was banned by the territorial government (and remained so until the 1970's), there were a few places where it was spoken as the everyday language.
One of these places was Ni'ihau, which managed to remain isolated from the mechanizations of the regime on Oahu. As a result, Ni'ihauan Hawaiian (and there is a great deal of controverswy about this) might be the purest spoken. Hawaiian is still the first language of that place, though it has absorbed twentieth century words, like kamepuila (computer).