Marshall's Beach, San Francisco, California

This is a fun beach to explore at low tide, but be warned at high tide it may not be passable.  Also note that this is an isolated spot and popular nude beach during the afternoons, but mornings are safe.

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Twin Peaks, San Francisco, California

You can drive up to the top for a quick tourist pit stop or hike up from Glen Canyon Park or just explore the trails around Twin Peaks.