Both tributary creeks enter and mingle with the Ipswich proper in Middleton, proceed south into northern Peabody, then loop northwards through the municipalities of Danvers, Topsfield (crossing US Route 1 just south of the Topsfield Fairground, entering from the west turns northerly and runs the greater length of Teal Pond southwest to north, the east bank of which forms a part of the western border of Hamilton, and exits the lake turning easterly staying south of Ipswich Road to head through and between the Willowdale State Forest and Bradley Palmer State Park, then opens a gap from Ipswich road diverging southeasterly from the road and the south edge of the Turner Hill Golf Club to turn north and form the west border of the Julia Bird Reservation thence meanders north through settled Ipswich neighborhoods and directly through town center passing under MA 133 (County Road, aka. South Main Street) where it gradually begins widening until a mile beyond main Street it passes Nichols Field and the salt marsh floodplain begins. From Nichols it traverses a bit over joins with Plum Island Sound in connecting with the Atlantic Ocean at Ipswich Bay. There is always some flow from the river into the bay. However, the lower Ipswich and Plum Island Sound, as well as the lower four other rivers flowing into it, and the much larger Merrimack River to the north, are all tidal estuaries, so the water is brackish from mixing ocean born saltwater inland during flood tides, and the lands immediately along the banks, where not inundated some of the time, are nonetheless saturated by brackish water and support only hearty plants capable of tolerating the waters such as salt marsh hay. High tides cover all of Great Marsh and the flood plains of the lower rivers. Low tides uncover the mud flats, reducing the deep channels to small streams some often small enough one can hop across to fish elsewhere.