To continue on from my Old Slade Lane adoption, this could make it a circular walk of sorts.
Your're looking for a Jar, with a key as the other cache kept going missing and the jar seems to stay put.
This short series follows the Colne Brook along the bridleway and heads though a field of horses. They have never caused me any problems, but would advise all dogs kept on a lead. In fairness, they have never shown any interest of coming up and saying hello either!
You could do this as part of a round trip (incorp Old Slade Lane) Field can get wet and muddy after rain, but dries out nicely in the summer!
Beware the water, I wouldn't advise going for a swim!