River Arun: History, Tides, Wildlife & Walking in West Sussex
Follow one of West Sussex's defining rivers from the High Weald through the Arun Valley, past historic Arundel and its castle, to the English Channel at Littlehampton.
The River Arun is one of the great landscape features of West Sussex. It flows south from the High Weald, crosses the countryside around Horsham and Pulborough, passes through the chalk hills of the South Downs and continues through Arundel before reaching the sea at Littlehampton.
For walkers, the Arun offers an extraordinary variety of scenery: floodplain meadows, wetlands, historic bridges, riverside paths, wooded hills, chalk downland and some of the finest views of Arundel Castle and the surrounding historic landscape.
From the High Weald to the Sea
The River Arun rises from springs in the High Weald to the east of Horsham. It then flows south across West Sussex.
Near Pulborough and Pallingham it is joined by the Western Rother, its largest tributary. From this wider valley the river continues south towards the South Downs.
It eventually cuts through the chalk hills, passes Arundel and crosses the coastal plain before entering the English Channel at Littlehampton.
A Remarkably Tidal River
One of the Arun's defining characteristics is the influence of the tide. The tidal reach extends approximately 26 kilometres inland.
This creates a river landscape that changes dramatically during the day, particularly around Arundel and the lower Arun Valley.
Mudbanks, reed margins, exposed river edges and water levels can all change as the tide rises and falls.
The Journey of the River Arun
The River and the South Downs
The Arun provides one of the important natural corridors through the South Downs.
Around Amberley and Arundel the river crosses the chalk ridge, creating a broad valley through terrain that otherwise rises sharply on either side.
This meeting of river, floodplain and chalk downland creates an especially distinctive walking landscape.
From higher ground, walkers can look down across the Arun Valley towards water meadows, villages, woodland and the distant coast.
Arundel and the River
Few places demonstrate the historical importance of the River Arun better than Arundel.
The town developed beside a navigable river beneath the strategically placed castle. For centuries the Arun provided a transport corridor between the coast and inland Sussex.
Arundel became an important river port. In 1817 it was made a bonding port, allowing goods to be stored under customs control before duties were paid.
The river's navigability allowed goods to move inland, while canal connections also linked Arundel towards Portsmouth.
With the arrival of railways and modern road transport during the nineteenth century, the commercial importance of river traffic declined. The relationship between town and river, however, remains clearly visible today.
The River Arun Through History
| Period | River Role | Legacy |
|---|---|---|
| Medieval | Transport, fishing, drainage and agriculture helped support communities along the Arun Valley. | Historic settlements and reclaimed floodplain. |
| Early modern | Navigation became increasingly important for trade and transport. | River engineering and navigation routes. |
| 18th century | Improved navigation strengthened connections between inland Sussex and the coast. | Commercial river traffic and port activity. |
| 1817 | Arundel became a bonding port. | Important period in the town's commercial history. |
| 19th century | Rail and road transport gradually replaced much commercial river traffic. | Shift from port activity towards tourism and other industries. |
| Today | The river remains important for wildlife, recreation, drainage, flood management and landscape character. | Walking, boating, conservation and tourism. |
Places Along the River Arun
| Place | River Connection | Walking Interest |
|---|---|---|
| Horsham Area | The upper Arun begins in the High Weald landscape east of Horsham. | Woodland and rural countryside. |
| Pulborough | The Arun and Western Rother meet within the wider river valley. | Wetlands, floodplain and South Downs views. |
| Amberley | The Arun cuts through the chalk landscape of the South Downs. | Downland, river paths and panoramic scenery. |
| Arundel | Historic river port beneath Arundel Castle. | Castle views, riverside paths and historic town. |
| Littlehampton | The river reaches the English Channel. | Harbour, coast and riverside walking. |
Wildlife Along the Arun
The River Arun and its floodplain provide a variety of habitats, including open water, wet grassland, reed margins, drainage channels, mudbanks and nearby woodland.
These habitats support fish, water birds, waders, insects and mammals. The wider valley is particularly valuable because river, wetland and floodplain habitats remain closely connected.
Around Arundel, conservation work has also helped restore populations of species such as the water vole.
Tides, Flooding and the Living River
The Arun is not a static landscape. Rainfall in the catchment, freshwater flow and the tide all influence river levels.
Because the tidal influence reaches far inland, communities including Arundel have a long history of managing flood risk and river defences.
Modern flood banks and tidal defences are therefore part of a much older relationship between people and the Arun Valley.
The River Arun and Our Arundel Circular Walk
The River Arun is one of the defining landscape features of our Arundel Circular walk.
The route explores the historic town before following the Arun Valley and surrounding countryside into the South Downs.
Water meadows, riverside landscapes and views towards Arundel Castle provide some of the most memorable sections of the walk.
The circular route is approximately 21 km / 13 miles and returns to Arundel at the end of the day.
Explore more about Arundel
Walking Beside the River Arun
The Arun Valley offers beautiful walking, but its riverside terrain requires sensible preparation.
Paths can become muddy after rain, while tidal sections and floodplain meadows can occasionally be affected by high water.
Stay on public rights of way, respect livestock and farmland, close gates where necessary and follow the Countryside Code.
Never enter flooded paths or attempt to cross water where conditions are unsafe.
Walk the River Arun and South Downs with us
Join Hiking in London Club for our Arundel Circular, exploring the River Arun valley, historic Arundel, rural villages and the beautiful South Downs countryside.
View the Arundel Circular – 21 km / 13 miles