A warp current, or subspace current, is an area of where subspace is in a state of motion relative to normal space. The currents affect the relative velocity of starships traveling within them. A ship traveling with the flow would have the effect of the warp field multiplied, allowing a ship to travel at a faster relative velocity. A ship traveling against a current would have its warp field weakened, requiring a stronger warp field to overcome the current's effects.