This is a souterrain, an underground gallery built during the early medieval period, typically constructed from dry-stone walling and used for storage, refuge, or both. The passage at Garrane appears to run east to west, though how far it extends beneath the ground remains uncertain, since the interior is no longer accessible.

Souterrains of this kind are relatively common across Ireland but rarely draw much attention, partly because so little of them is visible above ground. The Iveragh Peninsula in South Kerry, however, contains a particularly rich concentration of early medieval remains, and the site at Garrane forms part of a wider pattern of settlement across this landscape. The association of the souterrain with a hut of roughly circular outline follows a recurring arrangement seen elsewhere in the region, where underground chambers were integrated into, or placed close to, the domestic structures of small farming communities. The site was recorded and described by A. O'Sullivan and J. Sheehan in their 1996 archaeological survey of the Iveragh Peninsula, published by Cork University Press.