One of the toughest?
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The Macmillan Seabank Marathon is being held for the 37th time and all proceeds raised are split between Macmillan Cancer Support and a charity of the runners choice.
There is also a team relay that is based on teams of 8. Fun runners and walkers are welcome too.
The course starts in The Market Place of Boston and after running through the streets of Boston joins the banks of the River Haven.
After a few miles the route becomes quiet country lanes, and then farmland before joining the seabank. This can be rough in places.
Do you want to enter a relay team?