Zim Zim Falls is a waterfall in northern Napa County, California, within the Knoxville Wildlife Area and the broader Berryessa-Snow Mountain National Monument. The falls descend more than 100 feet on Zim Zim Creek, whose water flows into Eticuera Creek and ultimately Lake Berryessa. Public access began in 2005 after the wildlife area expanded by 12,000 acres. Set in a protected backcountry landscape, the falls are recognized as one of the notable natural features in this remote part of Napa County.