According to the United States Census Bureau, the township has a total area of , of which are land and , or 1.78%, are water. Loyalsock Creek, a southwestward-flowing tributary of the West Branch Susquehanna River, forms the southeastern border of the township. Wallis Run flows through the center of the township, first westward then south, to join the Loyalsock near the southern border of the township. The northwestern edge of the township drains by small streams to Lycoming Creek, another tributary of the West Branch of the Susquehanna. thumb|Rose Valley Lake in Gamble Township, looking west across the lake Rose Valley Lake is a reservoir that covers in Gamble Township. Its outlet is Mill Creek, which flows south to join Loyalsock Creek near Montoursville. The fish and waters of the lake are managed by the Pennsylvania Fish and Boat Commission. The lake is owned by the Commonwealth of Pennsylvania. Its primary use is recreational game fishing. The lake is open for recreational fishing on a year-round basis. Ice fishing is permitted, but the thickness of the ice is not monitored by the Fish Commission. The most common game species of fish in the lake are: largemouth bass, bluegill, black crappie, muskellunge, yellow perch, chain pickerel, pumpkinseed and walleye. The lake is east of U.S. Route 15 and Pennsylvania Route 14. It can be reached by taking Trout Run Mountain Road to Rose Valley Mountain Road.
According to the United States Census Bureau, the township has a total area of , of which are land and , or 1.78%, are water. Loyalsock Creek, a southwestward-flowing tributary of the West Branch Susquehanna River, forms the southeastern border of the township. Wallis Run flows through the center of the township, first westward then south, to join the Loyalsock near the southern border of the township. The northwestern edge of the township drains by small streams to Lycoming Creek, another tributary of the West Branch of the Susquehanna. thumb|Rose Valley Lake in Gamble Township, looking west across the lake Rose Valley Lake is a reservoir that covers in Gamble Township. Its outlet is Mill Creek, which flows south to join Loyalsock Creek near Montoursville. The fish and waters of the lake are managed by the Pennsylvania Fish and Boat Commission. The lake is owned by the Commonwealth of Pennsylvania. Its primary use is recreational game fishing. The lake is open for recreational fishing on a year-round basis. Ice fishing is permitted, but the thickness of the ice is not monitored by the Fish Commission. The most common game species of fish in the lake are: largemouth bass, bluegill, black crappie, muskellunge, yellow perch, chain pickerel, pumpkinseed and walleye. The lake is east of U.S. Route 15 and Pennsylvania Route 14. It can be reached by taking Trout Run Mountain Road to Rose Valley Mountain Road.