Agusan del Sur

      is a landlocked province of the Philippines located in the Caraga region in Mindanao. Its capital is Prosperidad and borders, from the north clockwise, Agusan del Norte, Surigao del Sur, Davao Oriental, Compostela Valley, Davao del Norte,Bukidnon, and Misamis Oriental.

Agusan derived its name from the local dialect, "agasan", meaning "where the water flows", referring to the great river splitting the land and meandering south to north in a 250-kilometer rush to Butuan Bay. Agusan River - the third largest in the country - served as highway for the Spanish colonizers in gaining access to inner northeastern Mindanao.