Dogs are welcome at Douglas State Forest in Massachusetts. This pretty park borders both Connecticut and Rhode Island, a great location for accessibility from all over the area. You can hike on miles and miles of woodland trails around the centerpiece of the park, Wallum Lake. Visitors love fishing in the water, picnicking on the shore of the lake, and jumping in a boat. Bring Fido with you to enjoy the park, as long as they are on a leash and all mess is cleaned up after them. Douglas State Forest is open every day of the week from sunrise to sunset.