Stillwater is a borough in Columbia County, Pennsylvania, United States. The population was 194 at the 2000 census. It is part of the Bloomsburg–Berwick Micropolitan Statistical Area.
Stillwater is located at 41°9′1″N 76°22′0″W / 41.15028°N 76.366667°W / 41.15028; -76.366667 (41.150244, -76.366751).
According to the United States Census Bureau, the borough has a total area of 3.1 square miles (8.0 km²), all of it land.