I know this is a hot topic, but what is a lake of Fire..... isn't a lake usually made of water.....?

Burning ges: 25 yrs ago scientists wrote about a "black Hole" on a supposed collision coarse to earth & discovered Gravity pulled it into itself so strong that light does not come out of it & discovered it is feeding on things in its path,but also upon it's own energy making it the only eternal force ever discovered.>>>>and they will be cast into the lake of fire & there will be grinding of teeth...