Zim Zim Falls, Waterfall in Knoxville Wildlife Area, California, US

Zim Zim Falls is a waterfall over 100 feet tall in the Knoxville Wildlife Area, in northern Napa County, California, within the Berryessa-Snow Mountain National Monument. It drops along Zim Zim Creek, a tributary of Eticuera Creek whose water eventually reaches Lake Berryessa.

Zim Zim Falls became reachable by the public in 2005, when the Knoxville Wildlife Area was enlarged by 12,000 acres. Before that expansion the waterfall lay on land without public access. The wildlife area is now part of the Berryessa-Snow Mountain National Monument.

The name Zim Zim comes from Zim Zim Creek, the stream the falls drop into; that creek feeds Eticuera Creek and eventually Lake Berryessa. Visitors today walk the Knoxville Wildlife Area trails to the falls, land opened to the public only in 2005.

Reaching this waterfall requires at least two hours of hiking over terrain that changes in elevation and ground conditions throughout. Sturdy footwear and a water bottle are essential, as shaded rest spots are few along the trail.

Zim Zim Falls sits in the Knoxville Wildlife Area, itself part of the Berryessa-Snow Mountain National Monument. The falls drop more than 100 feet, and their outflow joins Eticuera Creek before reaching Lake Berryessa. The creek below the falls carries that water north through Napa County's backcountry.