по реке

along the river; on the river

→ по

phrase Rare #32,366

along the river; on the river Used with the instrumental case to describe movement or location along/on a river. With вниз, вниз по реке means “down the river” or “downstream.”

RU: Мы плыли по реке до самого вечера.

EN: We traveled along the river until evening.

По реке плывёт мячик.

A ball is floating down the river.

Нет, когда я был маленьким, то плавал по реке.

No, when I was little, I used to swim in the river.

— Ночи Кабирии (1957)