Guesalaga Peninsula is a small, L-shaped, low-lying shingle covered peninsula on the east side of Discovery Bay, Greenwich Island in the South Shetland Islands, Antarctica forming the northwest coast of Iquique Cove and the north side of its entrance. The feature is projecting 700 m (766 yd) southwestwards and 300 m (328 yd) wide, with the narrow shingle Reyes Spit (62°28′46.3″S 59°40′29″W / 62.479528°S 59.67472°W / -62.479528; -59.67472) extending 400 m (437 yd) southwestwards from its west extremity Reyes Point (62°28′44″S 59°40′13.3″W / 62.47889°S 59.670361°W / -62.47889; -59.670361) into Discovery Bay. The Chilean Antarctic base Arturo Prat is situated on the peninsula.