This well, associated with St Doolagh and also dedicated to the Blessed Virgin, sits roughly 25 metres from the medieval church that shares its name, in the townland of Saintdoolaghs. A companion well, St Catherine's, lies just upslope. The little octagonal structure, its walls nearly a metre thick and its interior entered by way of a sunken court, bears a close resemblance to St Sylvester's Well in Malahide Village, suggesting a tradition of purpose-built well enclosures in this part of Fingal that has not received much wider attention.

The building's interior was once considerably more elaborate than it appears today. In 1609, a Mr Fagan of the nearby Feltrim family painted frescoes on the walls; these were still partially visible in the late nineteenth century, when W.F. Wakeman noted the small holes in the masonry where iron pins had once secured pictures to the stone. D'Alton's 1838 account describes the subjects: the Descent of the Holy Ghost at the top, with the figures of Saints Patrick, Columba, and Brigid around the sides, and the patron saint himself shown in a hermit's habit. A marble slab carried a Latin inscription comparing the well's healing waters to the pool of Bethsaida and claiming that St Doolagh's prayers had given it power to drive away fever and restore strength to the sick. The well attracted pilgrims at certain seasons, a practice that irritated the English writer Barnaby Rich, who in 1610 complained that Dublin was so placed that a Catholic could travel from the city's high cross, with the wind behind him in any direction, to reach either an "Idolatrous Masse" within the town or a "Superstitious Well" without it. Folklore collected from Kinsealy schoolchildren in 1937 still recorded the ritual for sore eyes: throw in a pin, rub the water on the affected area, and carry some away with you.

The well is visible from the road running between Malahide and Dublin, in a field to the right. It lies immediately south of St Catherine's Well and close to the ancient church and graveyard, so the three sites form a compact cluster worth taking time to read as a whole rather than in passing. The folklore accounts note a whitethorn bush growing nearby, which is a common marker of venerated wells in Ireland, and mention a feature in the adjacent field known as Saint Patrick's Bed, where water collects at certain times of year. The stonework of the enclosure is coursed masonry with well-shaped blocks, and the projecting gables on the cardinal points, each with a narrow pointed window above the string course, give the small building an oddly formal geometry that rewards a closer look than a roadside glance allows.