Sandy Lake is a borough in eastern Mercer County, Pennsylvania, United States.

[5] According to the United States Census Bureau, the borough has a total area of 0.8 square miles (2.1 km2), all land.

There were 330 housing units at an average density of 398.1 per square mile (153.7/km2).

The racial makeup of the borough was 99.33% White, 0.13% African American, 0.40% Asian, and 0.13% from two or more races.

24.5% of all households were made up of individuals, and 10.7% had someone living alone who was 65 years of age or older.