A leacht is a low cairn or platform of stones associated with penitential prayer, common at early Irish pilgrimage sites. The well is known as Tobar Olla Brenainn, meaning the Holy Well of St. Brendan's Anointing, and it sits roughly 400 metres from the Atlantic, which is audible if not always visible from the knoll. What makes the site quietly remarkable is not just its age but its relationship with the bog itself: one of the three stone crosses was, before renovation work in 1984, engulfed by approximately 0.9 metres of accumulated peat. The bog had been swallowing the site for centuries.

The physical evidence of age is considerable. Probing of a peat-face to the north revealed a stone trackway, 0.9 metres below the surface, composed of angular cobbles and boulders; radiocarbon dating of peat at the level of the stone layer produced a date of 1720±80 BP, placing it in the early centuries of the first millennium. One of the crosses appears to stand directly on this ancient approach path. The well itself is a slab-lined rectangular hollow measuring 0.8 by 0.7 metres and 0.5 metres deep, surrounded by coins, tokens, and small statues left by visitors. Three stone crosses stand at varying distances from the well, each crudely worked, with incised linear crosses on their faces; a cross-slab propped against the well's low protective wall carries several scored crosses, two of them more deeply cut than the rest, with a small encircled Latin cross in the upper quadrant of the largest. To the east of the knoll, slabs protrude through the ground surface, noted by scholars including Westropp in 1912 and Henry in 1957, and tentatively identified as the remains of a leacht some 5.2 metres by 3 metres in extent. In 1984, to mark the fifteen hundredth anniversary of St. Brendan's feast, peat was cleared from around the crosses and the well was rebuilt.

The folklore collected from local schools in the 1930s gives the site its narrative texture. In one account, Brendan was sailing by currach from an oratory on the Blasket Islands when a mysterious figure on the headland called him ashore. Led through what was then dense forest, later to become bog, the saint found two dying unbaptised men, administered baptism and last rites, and drew the water for the baptism from a spring on the spot. The guide vanished without explanation, and local tradition held that he was no earthly man. Two pillar stones were said to mark the burial place of the two men. A secondary strand of the story involves a nearby creek, blessed by Brendan on his landing, which subsequently became abundant with fish until Sabbath-breaking fishermen brought a curse of barrenness upon its waters. The path by which Brendan climbed the cliff is named Staighre Breanndhán, and the rock where he landed is called Leac Bheannuighthe. On the saint's feast day, pilgrims still perform the rounds at the well, walking between the crosses and reciting prayers, much as Delap recorded them doing in 1911.