Before it was Swanlinbar, the area was called Sra-na-muck, which translates as the valley of the pigs. The modern official Irish name is An Muileann Iarainn, meaning the iron mill, a reflection of the ironworks established here in 1700. The four entrepreneurs whose surnames made up the new name took out a lease in 1682 from Adam Loftus for lands in the area. By 1706, the iron works, land and town of Swanlingbar appeared in the will of Richard Darling of Dublin. By 1707, Robert Saunders had devised the works to his son Morley Saunders. The ironworks lasted longer than any of the four founders, surviving into the eighteenth century before finally exhausting the available timber. As the Reverend William Henry wrote in his 1739 book Upper Lough Erne, the forests of oak along the riverbanks had been so entirely extirpated to supply the iron-works that there was scarce a stump left.

As the ironworks declined, Swanlinbar discovered a different economic future. About half a mile from the village, mineral springs produced water rich in sulphur, salts, and what one eighteenth-century guidebook called fossil alkali. The Post-Chaise Companion of 1786 gave detailed instructions for visiting the spa. Guests went to bed at ten without supper, appeared at the spa well at six in the morning, drank the waters until nine while taking constant exercise, breakfasted around ten, returned to the well at one to drink two or three more glasses, and went home at three to dress for dinner at four. There is no particular regimen necessary, the guidebook noted, but to be temperate in wine, and to drink as little Chinese tea as possible. The waters were considered excellent for scurvy, nerves, low spirits, and bad appetite. From April to September, the village filled with gentry from across Ireland.

In his 1732 book A natural history of the parish of Killesher, the local rector Reverend William Henry described the social mixing at the spa in unusually vivid terms. He painted what he called an idyllic picture of the fine beau and the country girl with her hair plaited behind, the nice lady and the ploughman tilting most merrily together in a country dance by five o'clock in a morning, with the bagpiper playing tunes such as The Black Joke or Westmeath Election. Spa towns were often places where class barriers loosened, at least temporarily. Henry's description suggests that Swanlinbar, in its early eighteenth-century heyday, was no exception. The aristocracy from Dublin and the surrounding counties came to take the waters, but the local peasantry joined the dances. By 1769, John Wesley, the founder of Methodism, preached at the town's end and noted in his journal that he found near Swadlinbar as artless, as earnest, and as loving a people as even at Tonny-Lommon.

In 1786, a fire destroyed twenty-two houses in Swanlinbar. The village never quite recovered. By the time Bishop John Jebb, who had been the Protestant curate of Swanlinbar in 1799-1801, returned in 1824 after a twenty-three year absence, he found a sad transformation. He met, with a pastor's feelings, some whom he had catechized, and others whom he had baptized, but the village itself, in his day a fashionable resort, had been long deserted as a watering-place, and was already fallen into decay. The 1836 Ordnance Survey Namebooks confirmed his impression: This small town was in great repute about the year 1800 owing to the healing virtues of its spa water. But this has long ceased to please the public taste, and the town is at present little better than a country village. Samuel Lewis, writing in 1837, recorded that the post-town then contained seventy-nine houses, though the spa was still in operation in an enclosure tastefully laid out in pleasant walks and embellished with thriving plantations.

John Jebb himself left one of the more memorable accounts of life in Swanlinbar. In a letter dated 18 January 1800, written during his curacy, he described being called out at no very seasonable hour to visit a sick parishioner. The journey took him through snow, and bog, and mountain. So disagreeable a walk I never before experienced, he wrote. Some of the places through which I passed were nearly impassable; and, to increase my annoyance, I was obliged to return, partly on foot, partly on horseback, through this bleak and marshy tract, in darkness and intense frost. He concluded, however, that he enjoyed the satisfaction of thinking I was discharging my duty. He went on from Swanlinbar to become Bishop of Limerick. The walk through snow and bog was, perhaps, useful preparation.

Modern Swanlinbar is a small village sitting on the N87 road near the Fermanagh border, close to the Cladagh river. It has produced its share of notable people. Michael McGovern, the Northern Ireland international goalkeeper, was born in nearby Enniskillen. Owen Roe McGovern played Gaelic football for Cavan. Patrick McGovern served in politics. Thomas McGovern became Roman Catholic Bishop of Harrisburg in Pennsylvania. The village's Gaelic Athletic Association club is Swanlinbar St Mary's. The spa is gone, the ironworks long abandoned, the dance floors silent. But the name, in all its constructed absurdity, the joke that Jonathan Swift could not resist sharpening his pen on, has lasted three centuries and shows no sign of going anywhere.