How Do I Make A River With A Current?

I have a standard Unity First Person Controller, and a cube in some terrain made to look like a river. How would I go about making it so when the player walks into the river, they are pushed in a certain direction? Like if the river had a current and wasn’t just an aesthetic piece of scenery?

@superventure had a good suggestion after all, I just forgot to put Space.World in my Translate; once I did that it worked pretty well.

I placed a large cube/as a trigger sized approx to the river and added script

using UnityEngine;    
public class QM_Current : MonoBehaviour {

	void OnTriggerStay (Collider other) {
		if(other.tag == "Player") 
			other.transform.Translate(-Vector3.right * Time.deltaTime, Space.World);
		
	}

}

(for a current going right to left, change the Vector3.dir to suit your needs.