Ferry Beach State Park is located off Maine Route 9 on Bay View Road between Old Orchard Beach and Camp Ellis in Saco. A stand of tupelo (black gum) trees, rare at this latitude, can be seen in this 100-acre area, which offers a sweeping view of miles of white sand beaches between the Saco River and Pine Point. Long before highways were common north of Boston, beaches provided travelers relatively safe and easy transportation routes. A ferry crossing at nearby Saco River served beach travelers, and thus Ferry Beach State Park received its name. A picnic area, nature trails, guided nature programs, and changing room are available. Dogs are not allowed on the beach from April 1st September 30th.
I'd almost call it walking over hiking. Trail is flat but a nice mixture of woods and beach. To get to the beach you go through a tunnel that goes under the road, but it is still easy access to the road so I'd recommend holding onto your dog as you get close. The gate is closed in the winter, but a good walk, very easy hike, or snowshoe.