Water hole in dam : Bing screen

Have you ever seen a hole like this before ?
I had never seen this until I saw this on the screen of Bing.

Bing is a search engine of Microsoft (probably), and is naturally the default search engine of the Internet Exploer. I'm using Chrome at home and Firefox at the office, but open IE once a day for work to fill in what time I come to and leave the office every day with an internal web page. This kind of internal pages usually works only with IE. My IE setting is default setting and don't feel like customizing it, so I see the screen of Bing every day when I do daily work for that. I, however, like one feature of Bing more than any other search engine. My favorite feature is that Bing shows us a daily picture with some explanation, and this picture is usually amazing picture which I have never seen until I see it on the screen of Bing. I found the most interesting picture on the daily screen last week, that is the picture shown above. This seems like a hole in dam to adjust the amount of water because water is usually adjusted by opening and closing the gate of dam. I'm not sure why this image intrigues me, but it might be because this look like mysterious hole which never exists naturally and I would never be able to come out once I fall. I found the video of the hole below. It's worth watching how it works.

Did you watch this ? 
It's super scary for me just by imaging falling into this hole ...

Picture link