Lough Gowna and Sonnagh Fort

Overview

Lough Gowna (Loch Gabhna) sits quietly on the Longford–Cavan border, its 1,800-acre surface shaped by glacial moraines at the end of the last ice age. The lake’s shallow, weed-rich waters wind through a classic drumlin landscape, fed by the River Erne and carving out a network of sheltered bays and hidden inlets. Overlooking the eastern shore from a raised drumlin ridge is Sonnagh Fort, a well-preserved bivallate ringfort that frames the lake with sweeping views and a direct connection to Ireland’s early medieval past. Together, the lake and the fort make for a rewarding day out, whether you are casting a line, paddling across calm waters, or tracing ancient earthworks.

Location & Getting There

Lough Gowna lies roughly 12 km north-west of Longford town. The lake is easily reached by car, with several public launch sites providing gravel slipways and limited parking. On the Longford side, access points at Dernaferst, Lisanny and Dring cater to boaters and walkers, while the Cavan side offers slipways near Cloone, Aghanoran and Corfree. For visitors seeking additional amenities, the nearby villages of Ballinalee and Aughnacliffe provide larger car parks, public toilets and a selection of cafés. Sonnagh Fort is situated about 1.2 km west of the lake’s edge, reachable via a short, well-maintained footpath from the Dernaferst launch area.

History & Heritage

Lough Gowna & Inchmore Island

Local folklore attributes the lake’s formation to a supernatural calf that fled a well in Rathcor, carving out the waterway as it ran. The lake’s most significant historic landmark is Inchmore (Inis Mór), a substantial island in the south-western arm. Saint Colmcille established a monastery here in the sixth century, making it an early centre of learning and pilgrimage. The site faced Viking raids in 804, was later re-established by Augustinian monks in the twelfth century, and ultimately dissolved under Henry VIII in 1543. Stone foundations still mark the island’s layout, and a fifteenth-century church bell salvaged from the ruins now hangs in the parish church in Aughnacliffe.

Sonnagh Fort

Sonnagh Fort (Ráth an tSonnaigh) is a National Monument and the finest surviving example of the seven ringforts that once dotted the Aughnacliffe area. The bivallate enclosure features an inner bank rising between 0.5 and 0.9 metres, with an outer bank reaching up to 1.9 metres. Spanning roughly 46 metres in circumference, the site covers 0.39 hectares and dates to the Bronze or Iron Age (c. 2400 BC – AD 400). Though privately owned, it is protected by the State through the Office of Public Works. A natural spring located just to the east of the fort would have provided a reliable water source for its early inhabitants. The Irish name sonnach translates to “palisade”, reflecting the defensive double bank and ditch that characterise the structure.

Activities & Recreation

Fishing

Lough Gowna has a long reputation as one of Europe’s top coarse-fishing lakes. Pike are the primary target, with consistent catches throughout the year. Anglers typically see peak activity during the spring and autumn months, when feeding patterns intensify. Perch and roach are also commonly caught, particularly from boats that can navigate the weed-laden shallows near the launch sites.

Boating, Kayaking & Paddle-boarding

The lake’s sheltered bays and calm surface make it ideal for small craft. Kayaks and paddle-boards can be launched from any of the public slipways, offering a peaceful way to navigate the intricate shoreline and reach Inchmore Island. The lack of heavy commercial traffic means visitors can often enjoy complete solitude on the water.

Walking, Wildlife & Picnics

Gentle pathways follow much of the lake’s perimeter, passing through planted woodlands, peat-bog fringes and designated wildlife zones. Birdwatchers frequently spot mute swans, whooper swans, wigeon and various wading birds, particularly during migration seasons. The flat, accessible terrain makes it straightforward to pack a picnic and find a quiet spot by the water, with the earthworks at Sonnagh Fort providing a natural extension for a longer stroll.

Visiting Sonnagh Fort

The ringfort is an open-air archaeological site that invites self-guided exploration. Visitors can walk the perimeter to examine the double bank and ditch system, step through the 4-metre wide south-eastern entrance, and observe how the landscape was engineered for defence. The nearby spring remains a visible feature, grounding the site in its practical medieval context. From the ridge, the view stretches across Lough Gowna’s drumlin-fringed waters and out toward the surrounding plains. The adjacent wetlands also draw a steady variety of birds, adding a quiet natural soundtrack to the historic setting.

Practical Information

• Access & Cost: Both the lake’s launch points and Sonnagh Fort are free to access. The fort is unguided and has no on-site facilities; visitors should use the parking, toilets and refreshment options in Ballinalee or Aughnacliffe.
• Management: Sonnagh Fort is State-owned and maintained by the Office of Public Works (OPW). Lake amenities are overseen by local county councils.
• Opening Hours: Open year-round with unrestricted access. Launch sites remain available in all seasons, though boating conditions depend on weather and water levels.
• Visitor Tips: Bring appropriate fishing licences and tackle if angling, wear sturdy footwear for navigating the ringfort’s earthen banks, and pack a waterproof layer for unpredictable Irish weather. A picnic basket makes the most of the lakeside setting.
• Safety & Etiquette: Follow local fishing regulations, stay on established paths to protect the fragile earthworks, and respect the quiet character of the area. Dogs are welcome but should be kept under control near wildlife zones and archaeological features.

Nearby Attractions

A short drive from the lake brings you to Leebeen Park, which offers additional lakeside walks and ancient dolmen sites in the Aughnacliffe area. For those interested in local heritage, Ballinalee features a heritage centre and convenient amenities for longer stays. Further afield, Longford Town provides access to St Mel’s Cathedral and a range of dining options, making it a practical base for exploring the wider region.

Planning a visit around the spring or autumn months aligns well with peak fishing activity and comfortable walking conditions, while the summer season offers the calmest waters for paddling and boat trips.