Great Ouse River

At 143 miles long the Great Ouse is one of the longest rivers in Britain.
Running from it's source in Syresham, South Northamptonshire it travels mostly north and east through Buckinghamshire, Bedfordshire, Cambridgeshire before ending at Kings Lynn in Norfolk where it enters The Wash and the North Sea.
Over the the centuries the course of the river has been changed many times to make navigation easier and reduce flooding, starting as early as the 13th century.
The mid 1600s saw major changes in the course of the river to coincide with the draining of The Fens