The Fen Line is a railway in the United Kingdom that runs between the cities of Cambridge and Ely Cambridgeshire and the town of King's Lynn, Norfolk; the line is so called because it runs through The Fens. The line is part of the Network Rail Strategic Route 5 and comprises SRS 05.06 and part of 05.05. It is classified as a secondary line except between Cambridge and Ely which is classified as a London and South East commuter line.