History
This valuable nature area has developed on a site that was originally a military base.
The first defences, built 1544, protected the city and port of Portsmouth from inland attack for 300 years, before the existing Lines replaced them in 1871 when the renewed threat of a French invasion prompted the construction of stronger defences.
This two-mile long structure of chalk and earth ramparts 9m high and 20m wide, has six bastions of bombproof casemates and a moat to the north. The expected invasion never happened and Hilsea Lines have never been used in battle.
Most of the original structure is unaltered today. The Lines were designated a Scheduled Ancient Monument in 1964, and gained Conservation Area status in 1994 in recognition of the value, not only of the monument, but also of its setting.
Wildlife
The site of Hilsea Lines has become the most varied wildlife haven on Portsea Island, containing within its 80 hectares woodland, hedgerows, meadows, both fresh and brackish water areas, marshland and coastal habitats.
Here is a small selection of the wildlife here:
- Mammals and birds: Field Vole, Kestrel, Dunlin, Kingfisher
- Reptiles and beetles: Smooth Newt, Stag Beetle
- Butterflies and moths: Small Tortoiseshell butterfly, Garden Tiger Moth, Emperor Dragonfly – the largest British dragonfly
- Flowers and plants: Lords and Ladies (Cuckoo Pint), Bee Orchid, Yellow Flag, Common Walnut Tree (not native to Britain but were planted in this area by the military to be used for rifle stocks and butts)
The moat
The moat at Hilsea Lines, originally a single body of water, is now divided by a series of footpaths and bridges into four separate areas. These range from a pure seawater lagoon near Hilsea Lido with a good variety of crabs, shrimps and eels to two freshwater moats whose natural vegetation affords excellent wildlife habitats for water birds and insects.
The final moat is brackish water. This moat has an interesting contrast of habitat to the other moats and has flora and fauna that have adapted to the partially salty conditions.
Hilsea Lido
Hilsea Lido first opened in 1935 and quickly became one of Portsmouth’s most popular outdoor swimming destinations, welcoming generations of residents and visitors to its iconic open-air pool. In later years, a volunteer-led trust worked hard to keep the facility open, but despite their efforts the lido eventually closed and fell into disrepair.
Following a major renovation led by Portsmouth City Council and funded by the UK Government, Hilsea Lido has been brought back to life. The restored facility is now operated by the team behind Sea Lanes Brighton, an award-winning open-water swimming destination, bringing their expertise and passion for outdoor swimming to Portsmouth’s historic lido.
Find out more about Hilsea Lido
North Portsea Coastal Scheme
Sea defence work is going on until the end of 2026. This is the fifth and final phase of the North Portsea Coastal Scheme, which will safeguard more than 4,000 homes and almost 500 businesses in the north of the city. The work will include 1.3 km of flood defences with a design consisting of a sloped earth embankment, which provides the required flood defence level, with rock armour towards the creek.
Visitors can still be able to access Foxes Forest on the southern side of the moat. The Portsbridge carpark, near Portsbridge roundabout will be closed for the duration of the work.
Management plan
A Countryside Ranger oversees the day-to-day care and protection of the Hilsea Lines Conservation Area and all the wildlife habitats. Our long-term plans for the area are documented in a five-year management plan. To see the plan, email parks@portsmouthcc.gov.uk.
Volunteer work
The Hilsea Lines Ranger runs a healthy volunteer programme for anyone interested in participating in the valuable conservation and restoration tasks.
For volunteering opportunities, call the Ranger on 07958 353152 (answerphone facility) or email parks@portsmouthcc.gov.uk.
Address: Bastion 3, Scott Road, Hilsea. Due to the outdoor nature of the ranger’s work, please call first to check if he’s in the office.
Getting there
Hilsea Lines is easy to reach by bus, making it a great option for a car-free day out. Several routes stop close to the area, providing convenient access to walking trails, wildlife habitats, Hilsea Lido and other attractions. Find out which bus services serve Hilsea Lines and plan your journey in our guide.
Take the bus to Hilsea Lines and enjoy Portsmouth’s great outdoors.
Other options are available by bike, Vou rental bikes and e-scooters, train and by car.
Self-guided walks
There are Interpretation Boards throughout Hilsea Lines that highlight self-guided walks and emphasise some of the nature and history that can be seen along the way.
The leaflets below are useful for self-guided walks.
Documents
Hilsea Lines species list
Hilsea Lines wildlife leaflet
Hilsea Lines History Leaflet
