Main Dyke is a water channel running through the Fylde

The Fylde

The Fylde ; Scandinavian: "field") is a coastal plain in western Lancashire, England. It is roughly a 13-mile square-shaped peninsula, bounded by Morecambe Bay to the north, the Ribble estuary to the south, the Irish Sea to the west, and the Bowland hills to the east...

 area of Lancashire

Lancashire

Lancashire is a non-metropolitan county of historic origin in the North West of England. It takes its name from the city of Lancaster, and is sometimes known as the County of Lancaster. Although Lancaster is still considered to be the county town, Lancashire County Council is based in Preston...

 in England.

The Main Dyke is an outflow of the largely drained Marton Mere, Blackpool

Blackpool

Blackpool is a borough, seaside town, and unitary authority area of Lancashire, in North West England. It is situated along England's west coast by the Irish Sea, between the Ribble and Wyre estuaries, northwest of Preston, north of Liverpool, and northwest of Manchester...

, though Marton Mere originally released its waters via Spen Brook in the opposite directionhttp://www.btinternet.com/~stephen.yarwood/Blackpool_history.htm.

The Main Dyke joins the River Wyre

River Wyre

The River Wyre is a river in Lancashire, United Kingdom, which flows into the Irish Sea at Fleetwood. It is approximately 28 miles in length...

at Skippool, appearing to follow the course of an earlier "Skippon River" (named as such on John Speed's map of the county)http://www.lancashire.gov.uk/environment/oldmap/speed/speed.jpg.