A hop and a skip from town and only 3 miles from Redwood Retreat is Arcata Community Forest. There are several entry points to the forrest but the one I would recommend is through Redwood Park.
There are 2 parking areas at Redwood Park and the park is a great spot for a picnic and for the kids to enjoy the play structure. There is a large grass area that is enjoyed with folks playing soccer, frisby etc and all of this is surrounded by Redwood trees.
I Highly recommend for a quick (or lengthy) trek into the forest. Locals and visitors alike frequent this gem. Heavily shaded underneath the tree canopies and several degrees cooler than outside the park so bring layers. A true escape from town with not a sound of traffic, which you wouldn't believe given the proximity.
Arcata's Community Forest is comprised of approximately 790 acres of woodland recreation, with an exceptional network of developed trails for hiking, mountain biking and horseback riding (check the trail maps to determine which trails are open to bikes and horses). Trail Maps are available at the parking lots.