the Lost sea is a registered natural Landmark
the entrance building which contains the yellow man made tunnel that leads to the caverns
extensice cave system located in Sweetwater, Tennessee, USA. home of worlds largest underground lake.
Lost Sea Adventure
There is a tourest attraction called Lost Sea Adventure that gives guided tours of the caverns http://www.thelostsea.com/
tourist boarding for the boat portion of the tour this is the part were they see the Lost Sea