Just found this:

Frisian
Frisian is nowadays only spoken by about a quarter of a million people in the North of Holland and a few pockets in Germany and Denmark.
It is said that speakers of Frisian have little difficulty reading Old English: Frisian is closely related to the language of the Angles and Saxons that crossed the North Sea to England ca 500 AD/CE; but then there were 1500 years of separate development, English was greatly changed by the languages of the Vikings and the French of the Norman invaders, and Frisian was even more massively influenced by many centuries of Dutch rule.