A Bottomless Pit? No, but never swim near a water hole like this. http://bradsdomain.com/the-glory-hole... If you do see one of these, you're too close, and you better paddle your butt off to get away!
This really is called the Glory Hole named by local folks long before the term or words "Glory Hole" were considered pornographic. Monticello Dam at Lake Berryessa in Napa County, CA. hosts this drain also referred to as the "Morning Glory".
The reason it is called the "Black Hole" by Pilots of airlines or helicopters is because that's what they see from the sky (A Black Hole) when the "Glory Hole" is in action.
The Glory Hole has not been seen in action at Monticello Dam in Lake Berryessa since this video was taken back in MAY of 2007.
If you don't believe this is real and think the glory hole is a fake, Here's a Link to the actual location on Google Maps: http://bit.ly/6REAwz