All tidal rivers. For example - the Hudson's current changes direction four times every day as ocean tides pulse upriver to the Troy dam.
The nature of water is that water seeks its own level. Rivers are usually on land higher than the ocean, the higher the land is the faster it will flow, the lower the land is the slower it will flow. Rivers usually start in the hills or mountains, or sometimes a spring. The water wants to flow down with gravity; if it meets a natural obstacle such as rock or earth, it will eventually wear it away. Obstacle by obstacle it eventually flows to the ocean where it will level out with the water that's already in the ocean. Then it will flow no longer, now it is part of the ocean.
a delta
Tributaries
the Atlantic ocean
The Arctic Ocean
The rivers of western Europe flow toward the Atlantic Ocean and the North Sea.
Small streams flow into rivers and the rivers flow to bigger rivers.
All of the rivers in Siberia tend to flow north. These rivers flow north as they being pulled to drain into the Arctic Ocean.
Pacife
your mama's river
Wind!
the ones that are in America