The bird gives some sense of the scale. The haze is caused by all the water misting into the air.
After waiting to get down the elevator to the tunnels behind the falls, you line-up again to get your few seconds at one of these openings right behind the raging falls. Most people take selfies or family-portrait selfies. This image really doesn’t do justice to the full drama and fury of the water cascading past, right in front of you.