There's a little hairpin turn on the Akoni Pule highway, with a bridge and this stream running under it, just before the road ends at Pololu Valley. Most tourists drive right by, photographers hit the brakes and swerve into the turnout.
Sometimes the flow is pretty good, other times it's a dry gulch. I spent an hour rock hopping here with the camera, and slapping mosquitos. By the time we continued on and hiked down into Pololu, it was raining, and I got no more pictures that day.