San Pablo is a coastal municipality in the province of Zamboanga del Sur.
The municipality has a land area of 149.90 square kilometers or 57.88 square miles which constitutes 3.34% of Zamboanga del Sur’s total area. Its population as determined by the 2020 Census was 26,648. This represented 2.54% of the total population of Zamboanga del Sur province, or 0.69% of the overall population of the Zamboanga Peninsula region. Based on these figures, the population density is computed at 178 inhabitants per square kilometer or 460 inhabitants per square mile.