What direction refers to moving against the current of a river?

Moving against the current of a river is referred to as traveling upstream. This term is used because when you are going upstream, you are moving in the opposite direction of the water flow. This often involves more effort, as you are working against the natural flow of the river.

In contrast, traveling downstream means moving with the current, which is typically easier and faster as the water aids in the movement. The terms crosstream and lateral do not accurately describe the direction relative to the flow of the river, as they imply moving across the river or to the side rather than against the current. Thus, the correct terminology for moving against the river's flow is upstream.