The Witch Rock (Gróthúsvatnssteinn) is a glacial erratic on the shore of Gróthúsvatn lake, north of Sandur village. The boulder sits at the edge of a quiet lake in typical Sandoy landscape — green hillsides, farmland, and the sea visible in the distance — and is known locally for an unusual tradition: each summer women from the island deck the rock in knitted objects, creating a temporary installation of woolwork that celebrates both the craft tradition and something older and less easily named.
The walk to the rock from Sandur village takes about 45 minutes on a clear path, and the lake itself is worth the journey regardless of the season — swimming in Faroese lakes is not for the faint-hearted but the landscape is consistently beautiful. Ask locally for directions to the rock, as the path is not marked on all maps.