Testing out his Phantom drone, this quadcopter pilot launches into the air and happens to fly across a quarry that has become flooded. As he continues to fly, his drone captures some incredible footage of abandoned construction equipment that could not be saved before the flooding!

Cool video!
Sometimes the decision is made to simply abandon the equipment after the pit is dug. It is cost prohibitive to try and remove old equipment.There is one here in my area of Tennessee (not sure if this is it) but the story has it that the company was mining, and when using dynamite, they  accidentally blew a hole into an underground aquifer and this similar thing happened. They didn't have time to remove the equipment, because it flooded so fast.  Odd to find this video.  I'm quite old, but as a kid used to go fishing in a quarry near my rural home.  Not as large as this one, you could still see large abandoned equipment on the bottom.  The story from my family is that workers quarrying the limestone hit an underground water source under pressure.  Everyone got out, but none of the equipment.  This video is the only other reference to "drowned quarry equipment" I have ever heard of.  Wow,the cinematography was really good,the picyure and focus excellent,and the drone flew well.
Kudos to the operator,he know's his stuff.
And there really is treasure there,the lousy bastards that left it there surely could have given it away to a scrap yard, or somebody to make money out of it.
Instead,it sits there polluting away.