Not because it is sealed or flooded, but because a working railway was laid directly over it, and the ground has kept its secret ever since.

The cave at Caherdaly appears by name on the 1839 edition of the Ordnance Survey six-inch map, labelled simply as "Cave" in Roman script, which suggests it was a known, named feature in the landscape at the time of surveying. That first great Irish mapping effort in the 1830s recorded countless natural and man-made features that have since vanished, but most of those can at least be visited as empty ground or overgrown field corners. This one is different. The subsequent construction of the Galway-Limerick railway line consumed the site entirely, and today no visible trace of the cave survives at the surface. What kind of cave it was, how large, whether it had any local significance beyond its practical name, is not recorded.