There are a number of informal trails that join Amherst State Park with Glen Park in the village of Williamsville. These trails are beautiful, especially in the winter months.
You can reach this cache starting from either park but I suggest parking in the lot just south of Saint Mary's Apartments and coming in through Amherst State Park. It's a longer route, but easier terrain although after heavy rain you may need to get creative to keep your shoes dry.
Coming in from Glen Park is much shorter but requires a short scramble down steeper terrain on the West side of the bridge over the creek.
You are looking for a small lock and lock. Be careful in the winter months and have fun exploring these little known trails.