https://en.wikipedia.org/wiki/Freedom_to_roam:

“The freedom to roam, or "everyman's right", is the general public's right to access certain public or privately owned land, lakes, and rivers for recreation and exercise. The right is sometimes called the right of public access to the wilderness or the "right to roam".

[…]

The access is ancient in parts of Northern Europe and has been regarded as sufficiently fundamental that it was not formalised in law until modern times.”