At Henry Cowell Redwoods you can visit with ancient giants of the tree world. The tallest tree in the park is about 285 feet tall, and about 16 feet wide. The oldest trees in the park are around 1400 to 1800 years old.
There is a nature centre plus picnic areas, and catch release fishing is welcome on the Lorenzo River in winter though the rules are fine and should be checked ahead of time.
Over 20 miles of trails are available with varying degrees of length and difficulty, ranging from 0.4 miles long to 3.3 miles and including some seriously steep terrain so be sure what you're setting out on. Bikes are permitted on Pipeline Road, Rincon Fire Road, Ridge Fire Road, and Powder Mill Fire Road.