In 2004 scientist and researchers have claimed that "Krubera Cave" is the deepest cave in the world.
Its depth is 7000 feet.It is located in Abhkhazia,a republic district that belongs to Georgia.
This cave was discovered in the year 2001.There are several life forms found in dept of the caves such as transparent fish, parasite worms etc.
pictures are from http://www.amusingplanet.com/2014/07/krubera-cave-worlds-deepest-cave.html
http://globalcitiesdialogue.com/krubera-cave-the-deepest-cave-in-the-world
http://www.amusingplanet.com/2014/07/krubera-cave-worlds-deepest-cave.html
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From @hauntedbrain