Bayugan City, Bunawan, Esperanza, La Paz, Loreto, Prosperidad, Rosario, San Francisco, San Luis, Santa Josefa, Sibagat, Talacogon, Trento, & Veruela
The municipalities of Loreto, La Paz, Esperanza, and San Luis are the four largest municipalities in land area comprising almost 60 % of the province's total land area. Santa Josefa and Talacogon, also river towns, have the smallest land area.
Forestland constitutes 76% of the total land area or 6,827.5 km² while the alienable and disposable constitutes about 24% or 2,137.5 km². Present land use, however showed that settlements and commercial areas already occupy some of the forestlands.
Through the years, the province has lost so much of its forest resources because existing industries are extractive in nature.
Agusan del Sur is an elongated basin formation with mountain ranges in the eastern and western sides forming a valley, which occupies the central longitudinal section of the land. The Agusan River, which flows from Compostela Valley in the south towards Agusan del Norte in the north, runs almost in the middle of the valley and empties at Butuan Bay. The river has twelve tributaries: Wawa, Gibong and Simulao Rivers in the eastern side and Ojot, Pusilao, Kasilayan, Libang, Maasam, Adgawan, Cawayan, Umayam and Ihaon Rivers in the western side. These tributaries are fed by streams and creeks. The southern half of the province from the municipality of Veruela is an area filled with swamps and lakes, the biggest of which is Talacogon Lake.
The province is geographically situated below the typhoon belt but is usually affected by depressions forming in the typhoon regions of Visayas and the province of Surigao del Norte. The climate map of the Philippines based on the modified coronas classification shows that the province falls under Type II.
Type II climate has no dry season with very pronounced wet season of heavy precipitation. Maximum rainfall generally occurs from December to January although there is no single dry month. Its average monthly rainfall is 355 mm. and average temperature is 27.15 degree Celsius. Areas characterized by this climate type are generally along or very near the eastern coast thus are open to the northeast monsoon.