The river's source is in the foothills of
Albert County, near the rural community of
Goshen. It runs southwest through the community of
Penobsquis; several tributaries join the river in the town of
Sussex several kilometres further west. Between
Sussex and the river's junction with the
Saint John River at
Millidgeville (part of
Saint John), the Kennebecasis River runs through a well-defined river valley which has become one of the primary land transportation routes in the southern part of the province, hosting the
Route 1 expressway and the
Canadian National Railway line to the
Port of Saint John. The upper two thirds of the Kennebecasis River passes through pastoral rural countryside consisting of Acadian mixed forest and various agricultural areas, notably
dairy farms around Sussex. Southwest of Sussex, the river becomes increasingly larger as it passes the communities of
Valley Waters and
Hampton, before it empties into a
delta-like area informally called the Hampton Marsh. West of Hampton, the Kennebecasis flows in a broad
fjord-like glacial valley which defines the southern side of the Kingston Peninsula. At its junction with the Saint John River, the Kennebecasis River helps to form
Grand Bay. Several large islands can be found in the river, such as
Kennebecasis Island just off-shore from
Summerville on the Kingston Peninsula, and uninhabited (with the exception of a few summer cottages and an off-the-grid community on the southern part of the island)
Long Island, located near
Rothesay.
Hampton Marsh Image:River in Hampton.JPG|The river widens as it flows through the Hampton Marsh. Image:Hampton Marsh April.jpg|High water in the Hampton Marsh in April 2008. Image:Hampton Marsh June.jpg|The same area in June 2008, demonstrating the difference in water level. Image:Hampton Marsh.jpg|The lower end of the Hampton Marsh looking across to Darlings Island. ==Lower Kennebecasis River valley==