This is the 1274th most frequent German word.
entlang
"Entlang" means "along" in English.
'entlang' is used as a preposition, emphasizing the direction parallel to the river.
Wir gehen den Fluss entlang.
We are walking along the river.
'entlang' indicates movement on a defined path adjacent to the street.
Das Auto fährt die Straße entlang.
The car is driving along the street.
'entlang' here demonstrates adjacency to a linear feature like the forest border, used postscriptively.