Located in the northwest corner of
Ireland, Donegal is the island's northernmost county. In terms of size and area, it is the largest county in Ulster and the fourth-largest county in all of Ireland. Uniquely, County Donegal shares a small border with only one other county in the
Republic of Ireland –
County Leitrim. The vast majority of its land border (93%) is shared with three counties of
Northern Ireland:
County Tyrone,
County Londonderry, and
County Fermanagh. This geographic isolation from the rest of the Republic has led to Donegal people maintaining a distinct cultural identity and has been used to market the county with the
slogan "Up here it's different". While Lifford is the
county town,
Letterkenny is by far the largest town in the county with a population of just under 20,000. Letterkenny and the nearby city of
Derry form the main economic axis in the northwest of Ireland. Indeed, what became the City of Derry was officially part of County Donegal up until 1610. It is part of the
Northern and Western Region (a
NUTS 2 European statistical Region), within which it is part of the
Border strategic planning area. as seen from the
International Space Station Baronies and townlands There are eight historic
baronies in the county. While baronies continue to be officially defined units, they ceased to have any administrative function following the
Local Government Act 1898, and any changes to county boundaries after the mid-19th century are not reflected in their extent. The last boundary change of a barony in Donegal was in 1851, when the barony of Inishowen was divided into Inishowen East and Inishowen West. The barony of Kilmacrennan covers a large portion of northwest Donegal and is the largest in the county. With an area of , Kilmacrennan is also the largest barony in Ireland, being roughly equal in size to
County Monaghan. The smallest barony is Inishowen West, at . Townlands are the smallest officially defined geographical divisions in Ireland. There are 2,787 townlands in Donegal and an additional 47 historic town boundaries. These town boundaries are registered as their own townlands and are much larger than rural townlands. The smallest rural townlands in Donegal are just 1 acre in size, most of which are either lough islands or offshore islets (Corragh Island, Bishop's Island, Juniper Island, O'Donnell's Island, etc.). The largest rural townland in Donegal is 6,053 acres (Tawnawully Mountains). The average size of a townland in the county (excluding towns) is 438 acres.
Informal districts (
na Saighneáin) over Malin Head The county may be informally divided into a number of traditional districts. There are two
Gaeltacht districts in the west:
The Rosses (), centred on the town of
Dungloe (), and
Gweedore (). Another Gaeltacht district is located in the north-west:
Cloughaneely (), centred on the town of
Falcarragh (). The most northerly part of the island of Ireland is the location for three
peninsulas:
Inishowen,
Fanad, and
Rosguill. The main population centre of Inishowen, Ireland's largest peninsula, is
Buncrana. In the east of the county lies the
Finn Valley (centred on
Ballybofey) and The Laggan district (not to be confused with the
Lagan Valley in the south of
County Antrim), which is centred on the town of
Raphoe.
Geography cliffs, the second tallest in Ireland Donegal is the most mountainous county in Ulster. It consists of two ranges of low mountains, the
Derryveagh Mountains in the north and the
Blue Stack Mountains in the south, with
Errigal at the highest peak, making it the 11th-highest
county top in Ireland. It has a deeply indented coastline forming natural
sea loughs, of which
Lough Swilly and
Lough Foyle are the most notable. Donegal boasts the
longest mainland coastline of any county in Ireland, and has either the longest or third longest total coastline (including islands), depending on how it is measured. Estimates of the length of the coastline range from less than to . The official figure used by Donegal County Council is . The
Slieve League cliffs are among the highest sea cliffs in Europe, while
Malin Head is the most northerly point on the island of Ireland. Two permanently inhabited islands,
Arranmore and
Tory Island, lie off the coast, along with a large number of islands with only transient inhabitants. The 129 km long
River Erne, Ireland's ninth-longest river, enters
Donegal Bay near the town of
Ballyshannon. The River Erne, along with other Donegal waterways, has been dammed to produce
hydroelectric power. A canal linking the Erne to the
River Shannon was constructed between 1846 and 1860, creating Ireland's longest navigable waterway. The project was plagued with setbacks and closed in 1870, ten years after its completion. A joint effort between the Irish and Northern Irish governments restored the canal in the late 20th century, and the
Shannon–Erne Waterway reopened in 1994. Historically, the eastern boundary of the kingdom of
Tír Chonaill was demarcated by the
River Foyle. In the 17th century, an area of land west of the Foyle was transferred to the newly established city of Derry. The Foyle still demarcated a large section of Donegal's eastern border. To the south, the Drowes River forms a 9 km (6 miles) long natural boundary with County Leitrim. Donegal has a population density of 34.2 people per square kilometre, the lowest in Ulster and the fifth lowest in Ireland. The county has an expansive network of wildlife and conservation zones, including 46 European Union designated
Special Areas of Conservation (SACs) and 26
Special Protection Areas (SPAs), as well as 14
Natural Heritage Areas (NHAs), 74 proposed Natural Heritage Areas, 145 Irish Geological Heritage Areas (IGHs) and Ireland's second largest national park,
Glenveagh, which extends to over in northwestern Donegal. Owing to its scenic landscape and "
world-class wilderness", Donegal was named
National Geographic's "Coolest place on the Planet" in 2017. The county was also ranked the 4th best region in the world by
Lonely Planet's
Best in Travel series for 2024, which called Donegal "
purely wild with a big heart". The forested area in the county extends to , the 4th highest total forest cover in Ireland. Historic deforestation left Donegal devoid of forest cover by 1900. Much of the county's forests are commercial timber plantations, which were initially established in the 1930s as a way to create rural employment in areas with poor agricultural land and high rates of emigration. The county contains extensive tracts of
blanket bog which are concentrated in western and upland regions. Blanket bog covers an area of , or roughly 30 percent of the entire county.
Flora and fauna (
Aquila chrysaetos) Donegal has a wide variety of habitats, and over half of Ireland's plant and animal species can be found within the county. Approximately 11.4 per cent of the county is covered in forest, which is about average nationally. Forest cover is not evenly spread across the county, and some areas, such as
Pettigo and around
Lough Derg, are very heavily forested, while more exposed coastal and upland areas are virtually barren. Around 65 per cent of Donegal's forests are publicly owned. • The typical native tree species found in Donegal are
Scots pine,
aspen poplar,
birch,
hazel and
oak. Other common trees include
Sitka spruce,
mountain ash,
sycamore,
European larch and
horse-chestnut. • Many species of terrestrial and flying mammals live in the county, including
Irish hares,
brown hares,
red deer,
sika deer,
Irish bats,
common pipistrelle bats,
soprano pipistrelle bats,
brown long-eared bats,
whiskered bats,
Daubenton's bats,
Natterer's bats,
American mink,
pygmy shrews,
rabbits,
pine martens,
stoats,
badgers,
red squirrels,
gray squirrels,
wood mice,
house mice,
brown rats,
otters,
red foxes,
hedgehogs and
feral goats. • Marine mammals include
harbour seals,
grey seals,
humpback whales,
orcas,
pilot whales,
fin whales,
minke whales,
sperm whales,
Cuvier's beaked whales,
common dolphins,
bottlenose dolphins,
Atlantic white-sided dolphins,
white-beaked dolphins,
striped dolphins,
Risso's dolphins and (very rarely)
walruses. Despite its northerly latitude and geographic isolation, Donegal also hosts two species of amphibian (
common frog &
smooth newt) and two reptile species (
Leatherback turtle and
viviparous lizard). The native
Irish red deer in Donegal went extinct around 1860 and was reintroduced in the 1890s. Due to interbreeding, most of the deer in the county are now a Sika-Red deer hybrid. The Wild Ireland wildlife park near
Burnfoot showcases some of Donegal's historic animal species that were hunted to extinction, including
brown bears,
lynxes, and
gray wolves. In 2001, the golden eagle was re-introduced into
Glenveagh National Park and is currently Ireland's only breeding population. A survey of the macroscopic marine
algae of County Donegal was published in 2003. The survey was compiled using the algal records held in the
herbaria of the following institutions: the
Ulster Museum,
Belfast;
Trinity College Dublin;
NUI Galway, and the
Natural History Museum, London. Records of flowering plants include
Dactylorhiza purpurella (Stephenson and Stephenson) Soó.
Climate The majority of Donegal has a
temperate oceanic climate (
Köppen climate classification: Cfb), with upland areas in the
Derryveagh and
Blue Stack ranges classified as
oceanic subpolar (Köppen climate classification: Cfc). The county's climate is heavily influenced by the
North Atlantic Current. Due to the topography of western Donegal, it receives
orographic rainfall, where the air is forced to rise on contact with its mountainous coastline and subsequently cools and
condenses, forming clouds. The mountains of Donegal are among the cloudiest places in Ireland,, and northern Donegal is the windiest. Irish monthly record wind speeds for March, June, July, September, November, and December have all been set at
Malin Head. The highest wind speed ever recorded in Donegal was 181 km/h (112 mph) on 16 September 1961, during
Hurricane Debbie. However, due to its exposed coastal location, the climate at Malin Head is not representative of most of the county. Winds are much lighter in the county's interior, and temperatures are cooler in the winter and warmer in the summer. Annual rainfall in the county ranges from around in the lowlands of north-eastern Donegal to over in western mountainous areas. Precipitation exceeding 1 mm (0.04 in) will fall across all areas of Donegal on over 150 days per year. While the prevailing wind direction in Ireland is south-westerly, which brings warm, moist air from the
Gulf of Mexico, a low-pressure
Polar front regularly passes to the northwest of the island, bringing cold and unsettled weather to the region. The upland areas of Donegal will reliably receive some covering of snow every year. In lowland areas, snow - while still relatively infrequent - is more common than in the rest of Ireland. Despite its coastal location, Malin Head records an average of 20 days of snowfall per year. In contrast,
Valentia Island, a similarly placed coastal station in the southwest of Ireland, records just 3.
Geology and terrain Donegal can be divided into six main geological subdivisions. Of these, the most expansive sections are the
Lower Carboniferous limestones and sandstones of south Donegal, the
Devonian granite of the
Donegal batholith, which extends for about 75 km northeast to southwest from
Ardara to
Fanad Head, and quartzo-feldspathic
Dalradian rocks from the
Precambrian era, which cover much of the rest of the county. The geology of Donegal is very similar to that of
County Mayo, and both counties are located within the
Grampian Terrane. The oldest rocks in Ireland are a
granitic gneiss found on the island of
Inishtrahull, located ca. north-east of Malin Head. They are 1.78 billion years old, making them
Paleoproterozoic in age. The oldest rocks on mainland Donegal are a quartzo-feldspathic paragneiss found around Lough Derg, which have been dated to 1.713 billion years ago. Donegal is the most seismically active part of Ireland. The
Leenan Fault is a large
strike-slip fault that bisects the county from Lough Swilly to Donegal Bay, and dozens of tremors have been recorded along the fault since the late 19th century, although none have been larger than a magnitude 3 on the
Richter scale. The county's landscape was carved out by glaciation at the end of the
Pleistocene and the subsequent
retreat during the early
Holocene. Donegal contains one of Ireland's three glacial
fjords (or
fjards) at
Lough Swilly, the others being
Carlingford Lough and Killary Harbour. Lough Swilly is the county's largest inlet and forms the western boundary of the
Inishowen Peninsula. The thick ice sheet that once covered the region carved out deep basins in the Donegal uplands and many
tarns or corrie lakes developed in these depressions after the ice had melted, including Lough Maam below
Slieve Snaght and Lough Feeane under
Aghla More. Larger glacial lakes formed in the county's distinctive
U-shaped valleys, such as
Lough Beagh and
Gartan Lough in
Glenveagh, and
Dunlewey Lough and
Lough Nacung Upper in the
Poisoned Glen. Valleys such as these were the last areas to retain glaciers as temperatures rose. As the ice sheet thinned, topography became the dominant force driving the direction of ice and meltwater flow. Erosion by glacial meltwater carved out large channels in southern Donegal, which directed water and sediment to
outwash fans in Donegal Bay. The area south of Donegal town, where the
River Eske flows into the bay, is an example of one of these outwash areas. Sea levels in the area began to stabilise around 5,000 years ago, and the balance of erosion and deposition along Donegal's coastline resulted in the development of many sandy beaches and
spits interspersed with jagged sea cliffs. ==Demographics==