Cucumber Run is a long 3rd order tributary to the Youghiogheny River in Fayette County, Pennsylvania.
Cucumber Run rises about 2 miles southeast of Deer Lake, Pennsylvania, and then flows northeast to join the Youghiogheny River about 0.25 miles southeast of Ohiopyle.
Cucumber Run drains of area, receives about 51.1 in/year of precipitation, has a wetness index of 350.68, and is about 85% forested.