Usnea Plug is a volcanic plug, 30 m from base to summit, rising to 117 m in the interior of Byers Peninsula, Livingston Island in the South Shetland Islands, Antarctica. The area was known to 19th century sealers.
The feature's name derives from the genus of lichen, Usnea, prevalent on the plug and in this vicinity, and results from geological work by an American field party in early 1969.
The hill is located at -62.6417°N -61.0953°W which is 790 m southwest of Chester Cone, 3.47 km north of Nikopol Point, 5.54 km northeast of Devils Point and 2.77 km east by south of Laager Point (British mapping in 1968, detailed Spanish mapping in 1992, and Bulgarian mapping in 2005 and 2009).
