Ronald C. Caspers Regional Wilderness Park is a public park in Orange County next to Cleveland National Forest.
It's mostly a mixture of coastal sage scrub and chapparal, with some "riparian habitat" -- the mixture of trees and bushes that grow near creeks.
For many years, it didn't allow children because of two mountain lion attacks in 1986, but I understand it now does again. As far as I could tell from looking at the court testimony, the first attack was not the parents' fault in any way, but do keep an eye on any kids you bring along; many of the trails wind through fairly heavy brush.
The entrance is on Ortega Highway, about 8 miles inland from San Juan Capistrano, off the Interstate 5. Admission is $2.