What a fancy name for a brook, isn't it?
This cache will take you to the parking for the Bog Brook Conservation Area. Note that this is a Park and Grab, and I am bring you to parking.
Now for the puzzle. You choose which coordinates will bring you to the cache.
N 42 59.160 W 71 37.827
N 42 59.151 W 71 38.002
N 42 58.830 W 71 37.882