When paddling downstream paddlers can use some advanced paddle strokes along with differing currents to quickly turn their boat, one of these strokes is the duffek. In a river current generally moves downstream, but behind rocks or on shore the water may be still or actually move upstream. When a paddler moves from one of these currents to the other they can use the duffek stroke to quickly turn their boat into the direction of the current. A good visual representation of the duffek in real life is thinking about someone running down a sidewalk, grasping a pole on the sidewalk and swinging around it with legs outstretched to end up running in the other direction, momentum intact. In a kayak this can be achieved by putting a vertical paddle blade in the opposing current when crossing from one current to another. The hardest part of the duffek is keeping your paddle vertical right by your knee, and keeping the power face always facing exactly perpendicular with the current you are grabbing. In other words, the scoop of the blade always needs to be facing where the current is coming from. This is tricky because as you turn your blade will turn with you unless you twist your wrists to keep it static. If done correctly paddlers can enter and exit opposing currents with one duffek that can be turned into a powerful forward stroke upon completion.