In a different thread, Bower Cave was mentioned. There is an interesting article about it in the U D.
It is located on old highway 120 east of Groveland, about an hour west of Yosemite Valley.
http://www.uniondemocrat.com/2009041796454/News/Local-News/Bower-Cave-What-lies-ahead-for-this-buried-Mother-Lode-treasure