Looking at the main entrance to the Millerton Lake Caves near Awberry, California.  This unique granite cave system is cited as one of the world's best examples of a corrosional cave w/ nearly 1.5 miles of passages divided into three main sections.  This is the lower section just above the reservoir & I was only able to safely venture maybe 50 feet in (it was already quite dark this far in & to go further on one would preferably need a diving suit w/ proper footwear to grip the slick carved granite).  A stream flows throughout the cave, sometimes raging if it's a wet rainy year, making it impossible to explore.