Brunswick Peninsula (Spanish: Península de Brunswick) is a large peninsula in Magallanes y la Antártica Region, Patagonia, Chile, at 53°30′00″S 71°25′00″W / 53.5°S 71.4166667°W. It is 16 kilometres (9.9 mi) wide at its base in the north, and almost 80 kilometres (50 mi) in the south. The Strait of Magellan defines the eastern and southern limits while the Otway Sound (Seno Otway) delimits its western shores. It measures 115 kilometres (71 mi) in length from the base to Cape Froward, the southernmost point of the American mainland. This yields an area of more than 6,300 square kilometres (2,400 sq mi).