Formosa is a community located in the municipality of South Bruce, in Bruce County, Ontario, Canada. Neighbouring towns include Mildmay and Walkerton. The postal code for the hamlet is N0G 1W0. Rev. Gaspar Matoga, a Jesuit missionary, visited the area in January 1853, on one of many trips to minister to the new settlements of the region. Upon seeiā¦Formosa is a community located in the municipality of South Bruce, in Bruce County, Ontario, Canada. Neighbouring towns include Mildmay and Walkerton. The postal code for the hamlet is N0G 1W0. Rev. Gaspar Matoga, a Jesuit missionary, visited the area in January 1853, on one of many trips to minister to the new settlements of the region. Upon seeing the valley in which the present day hamlet is situated, he described it as formosa, the Latin word for beautiful.