The municipality is lying on the northeastern part of the province, located 8 kilometers from Dipolog City. It is bounded in the northwest by the city of Dipolog; in the northeast by the city of Dapitan, in the south by the municipality of Sergio Osmena, in the east by the municipality of Piñan and in the southwest by the municipality of Katipunan, with a geographic coordinates of 8o 31’ 59” N, 123o 22’ 0”
The slope of the area is one factor considered in determining the suitability of lands for developments as well as for crops cultivation. Levels to moderate sloping areas with good soil characteristics are favorable for cultivation and urban development. Strongly sloping to mountainous conditions makes the land highly prone to soil erosion and is mostly suitable for grazing and forest.
The municipality has a slope ranging from 0 to 50%. Based on slope classification there are approximately seventy five (75%) percent of the total land area that are best suited for cultivation of agricultural crops. These areas have slopes ranging from 0 t0 18%. About twenty five (25%) percent of the land areas have a slope ranging from 18% to 50% and are best suited only for pasture forest, or permanent crops. The level or almost level areas in the municipality are located within barangays of Pob. North, Pob. South, Labrador and Isis.
Polanco is generally plain especially in the rice land areas. Some parts are slightly mountainous like barangays of Linabo, Maligaya, Milad, De Venta Perla and Dangi. Two prominent rivers traverse the length of the municipality; Layawan River and Dipolog River, both rivers flow into the Sulu Sea at Poblacion of Dipolog City situated along the river banks are the corn granaries of the municipality.