Control Currents

Any sections of the area that intersect with a body of water become a current, flowing either away from you or toward you (each section must flow in the same direction). Creatures or vehicles that start their turn within the current or enter it for the first time on their turn are moved 10 feet in the direction of the current. Unwilling creatures or vehicles can attempt a Fortitude save to avoid this effect. Creatures or vehicles that move against the direction of the current treat it as difficult terrain.