One of my favorite places, the perfect coastal campground for checking out and roughing it. Tent & pop-up campers only, with limits on amplified noise and number campers makes it a great place to relax. Little to no cellphone service so might as well turn the phones off and enjoy nature. There are site options along the dunes, in the woods and along the cliffs of Joe's Head and Osprey Point.
Some great hiking trails and isolated beaches on the North side of the island. There is a pavilion near Sailboat Beach up to the left just before the end of Island Road which is a cool spot for a group to hang for the day. The all dirt roads are fun and easy for mountain biking. There's a few spots for cliff jumping, one in the Bathtub and another at Osprey Point. No motors, but there is boat access if you have and enjoy kayaking or canoeing (be sure to say hi to the seals!)
Be sure to load up at the Shaws in Bath, ME before heading down 209 towards Phippsburg. The campground store by the main entrance has the basics for camping in case you forget anything and will steam fresh lobster or clams to order. The Kelp Shed across from the store is a great place to hang if the weather turns or just to grab a snack (you need to try the Maine Blueberry Ice Cream!)