A souterrain is an underground stone-lined passage or chamber, typically associated with early medieval settlement, used variously for storage, refuge, or ventilation of a dwelling above ground. What makes this particular example quietly curious is that its entrance sat not at the edge of the enclosure but at its centre, an arrangement that hints at the passage extending some distance beneath the surface and perhaps serving a more elaborate function than simple food storage.

The site appeared on the second edition of the Ordnance Survey map as a recognisable rectangular enclosure, the kind of earthwork that in Ireland usually indicates the remains of a ringfort, a farmstead enclosed by one or more banks and ditches during the early medieval period. According to J. Cuppage's 1986 archaeological survey of the Corca Dhuibhne region, the Dingle Peninsula survey published under the title 'Corca Dhuibhne. Dingle Peninsula archaeological survey', the Red Cave was said to connect underground with a second ringfort located on the southern boundary of the townland. Whether that claimed tunnel between two separate enclosures was a genuine architectural feature or an elaboration accumulated over centuries of local memory is difficult to say now, but the idea of a passage running beneath the fields to link two fortified farmsteads is precisely the kind of detail that tends to attach itself to souterrains, which have long attracted folklore about escape routes and hidden depths.