Proppen (English: The Plug) is a small islet in the sound (Sluket or "The Gully") between Langåra and Rullesteinøya in Tiholmane, part of Thousand Islands, an archipelago south of Edgeøya.
Coordinates: 76°58.3′N 21°56.5′E / 76.9717°N 21.9417°E / 76.9717; 21.9417