This park on the far northern coast has the most lovely, moderately challenging hiking trail that winds through magnificent redwoods.  Humboldt County has really great old growth redwood groves.  The atmosphere is very quiet and serene.  Redwood Park has a flat grassy area with a playground right in the middle of the forest and trails at the edges that climb the hillside. Sorry about the crummy photo quality–these were taken a couple of years ago with my old 3GS iPhone.

Tree trunk archway.

The dappled light here is magnificent.

A tree growing out of the stump of another massive tree, slowly wrapping its roots around it down to the earth.