Coordinates: 53°36′47″N 2°59′28″W / 53.613°N 2.991°W The West Lancashire Coastal Plain is a large area in the south west of Lancashire, England.
The plain stretches from the Rimrose Valley in Seaforth, near Liverpool on the Mersey, to the south, to Preston on the Ribble, to the north. To the east, the plain is bounded by the foothills of the Pennines, while the western edge of the plain is separated from the sea by sand dunes. It is very flat, and much of it is only a few metres above sea level.
The terrain is mostly glacial in origin. The area has been inhabited since Neolithic times, though large areas would have been marshy and contained Martin Mere.
The WWT Martin Mere near the villages of Holmeswood and Tarlscough gives a glimpse of what this area was like before reclamation. The mere was, until reclamation, the second largest body of fresh water, behind Windermere. The rivers Mersey, Alt and Ribble feed into the plain and the flood plains add to the flatness.