cave with a lake

lake water pond cave limestone mountain underground inside ancient speleology geologic dark mineral tunnel cavern landscape geology nature hole old stone natural wall rough deep darkness corridor view travel mysterious rock formation prehistoric exploration speleotheme boulders earth fossil jurassic stalactites stalagmites gours flowstone speleogens moonmilk mondmilch speleothemes caving quail stalagmite wadi stalactite terrain canyon trunk arch temple wood cliff