St. Rose is located at (29.960421, -90.313094) [REF].
According to the United States Census Bureau, the CDP has a total area of 5.0 square miles (13.0 km²), of which, 4.0 square miles (10.5 km²) of it is land and 1.0 square miles (2.6 km²) of it (19.88%) is water.