the fens are reclaimed sea land that use to be underwater thousands of years ago and have now been drained off to produce a vast amount of flat open farming land to grow crops around Lincolnshire Cambridgeshire and Norfolk, these vast open spaces with a wide variety of crops for the hares to munch on have produced some of the best hares and coursing land in the country, if I won the lottery the first thing I'd do is buy a big estate in Lincolnshire, happy days, so basically the fens are just big fields