Consider Heading out to one of the outer islands like Sucia Island State Park, Matia Island State Park, or Stuart Island State Park. There are roughly a dozen remote island parks were you can hike, bike, rent kayaks or just sit on the beach and have a picnic. You can catch a water taxi and head out to one or if your an experienced boater you can rent a boat for the day and head out. There are lighthouses and fossil beds to explore. It hard to find a more authentic yet laidback adventure. A great way to spend the day getting to the roads less traveled in the San Juans outer island marine parks.