This is one of a series of cacches along the urban portion of the K&P Trail.
If you're coming from Downtown Kingston, the K&P Trail makes a 90 degree turn at River Street and follows the sidewalk for a while. This detour is to avoid "The "Brownlands", site of an old tanning plant that accumulated toxic chemicals in the ground for many years. Eventually this will be opened up for unrestricted use, but for now it's "use at your own risk" and possibly still dangerous for children and dogs. So make the turn and follow River Street to Rideau Street.