Terschelling Frisian
Terschelling Frisian, or Skylgersk, is a West Frisian language spoken on the island of Terschelling in the Netherlands. In the central stretch of the island a dialect of Dutch is spoken, but on the western and eastern ends of the island are spoken two Frisian dialects, known simply as Westersk and Aastersk, by about 800 and 400 people, respectively.