Geography thumb|Downtown Gladstone with Peapack in the distance. According to the United States Census Bureau, the borough had a total area of 5.80 square miles (15.03 km2), including 5.73 square miles (14.85 km2) of land and 0.07 square miles (0.18 km2) of water (1.21%).
Geography thumb|Downtown Gladstone with Peapack in the distance. According to the United States Census Bureau the borough had a total area of 5.80 square miles (15.03 km2), including 5.73 square miles (14.85 km2) of land and 0.07 square miles (0.18 km2) of water (1.21%)