Unterstein, Religious hermitage in Sankt Jakob in Defereggen, Austria.

Unterstein is a single settlement of two buildings on the valley floor of the Defereggental, on the left bank of the Schwarzach. The farmstead Bärs (Oberrotte 1) and the neighbouring house Oberrotte 83 stand just west of the Steinerbach stream, which separates them from the Unterrotte district. The Defereggentalstraße runs south of the buildings.

The settlement originated from the Salzburg Jesach estate, a 17th century property that existed as an enclave among other alpine farms. This foundation was part of the economic structure that shaped trade and management of the mountain region.

The name Stein refers to the rock above neighbouring Oberstein, not to Unterstein itself, which was placed west of the Steinerbach because the stream's outbursts made the original site unsafe. The two farmsteads are still called Bärs (Oberrotte 1) and Oberrotte 83, and the stream beside the latter marks the boundary with the Unterrotte fraction.

Unterstein is not a hermitage but a two-building hamlet on the valley floor of the Defereggental, on the left bank of the Schwarzach. The Defereggentalstraße runs directly south of the settlement, separating it from the river, and the Steinerbach flows just east of house Oberrotte 83, marking the boundary with the Unterrotte fraktion. The Bärs farmstead is listed as Oberrotte 1.

The Gasser family originated from this settlement, including physician Norbert Gasser who later served as chief doctor at the Lienz hospital. The connection shows how alpine villages produced educated professionals who made careers in larger cities.