The province is divided into two distinct geographic regions; the highlands of the Central Panay Mountain Range on the western border and the lowland plains which account for a larger portion of the province.
Expansive fishponds and mangrove wetlands are found along the coasts and rivers of Oton, Iloilo City, Leganes, Zarraga, Dumangas, Barotac Nuevo, Anilao, Banate, Barotac Viejo, Ajuy, Balasan, and Carles.