It is the line that marks the theoretical halfway point between the equator and the South Pole. The true halfway point is 16.2 kilometres (10.1 mi) south of this parallel because the Earth is not a perfect sphere but bulges at the equator and is flattened at the poles.
Around the world
Starting at the Prime Meridian and heading eastwards, the parallel 45° south passes through:
Co-ordinates Country, territory or sea Notes Atlantic Ocean Indian Ocean Pacific Ocean Tasman Sea New Zealand South Island, passing just north of the towns of Oamaru, Naseby, and Queenstown, and through the small settlement of Becks Pacific Ocean Passing just south of Guamblin Island, Chile Chile Islands in the Chonos Archipelago including James Island and Melchor Island, and the mainland intersecting Route 7 at Campo Grande roughly 100 km (60 miles) north of Coyhaique. Argentina Atlantic Ocean