Whiting Ranch Wilderness Park consists of 2,500 acres of arid rocky hills in Orange County, occupying what used to be part of a cattle operation started by Jose Serrano in 1842 and later purchased by Dwight Whiting. Convenient access from Portola Parkway makes the 17-mile trail system exceedingly popular with mountain bikers. This guide explores the eastern section along Serrano Creek, but you could extend the trail for another hour or two by exploring the western Red Rock Canyon sections as well.