St Rock's Well, associated with the area around Jamesgreen in Co. Kilkenny, sits in this uncertain category: known to local history, documented in print, but physically elusive in a way that sets it apart from the more visited sacred springs of the Irish countryside.

The well takes its name from its proximity to St Rock's Church, near the Fair Green, and was originally said to have sprung up in the centre of an area known as Walkin's Green. Over time it became swallowed by Walkin's Lough, a wet marshy turlough, which is a type of seasonal limestone lake that fills and empties according to groundwater levels, that covered the ground around it. The well had effectively disappeared from view by the nineteenth century, but in the summer of 1812 it made an unexpected reappearance. Workers digging in the turlough for manure, a common enough practice on waterlogged ground, broke through to find a range of stones placed so as to form steps, which in turn led down to an enclosure of irregularly shaped stones. The well had not been lost so much as sealed beneath the lake. Once the digging stopped, it was covered again by the waters. This account comes from the Kilkenny antiquary Hogan, writing in 1858 and 1859. He returned to the subject in 1883, noting that Walkin's Lough had been drained in 1830, though by that point the well appears to have left little lasting trace above ground.