Have to think about it a bit before I answer. I have walked quite far a number of times for a cache, not because the cache demanded it, but just because I decided to walk to it rather than drive to the closest parking spot. A particular cache is not jumping out at me as being the furthest walked though. I guess Mega Brek was a bit of a distance, but probably seemed more than it actually was due not being just straight walking, but I am not going to sit and plot the distance we did for that one just at the moment.