The Outer Harbor line is a suburban branch line in Adelaide, South Australia. It runs from Adelaide station through the north western suburbs to Port Adelaide and Outer Harbor. It is 21.9 kilometres (13.6 mi) in length, and shares part of its run with the Grange line. It is operated by Adelaide Metro.

Adelaide railway station is the central terminus of the Adelaide Metro railway system. All lines approach the station from the west, and it is a terminal station with no through lines, with most of the traffic on the metropolitan network either departing or terminating here. It has nine below-ground platforms, all using broad gauge track. The station is located on the north side of North Terrace, west of Parliament House.