The river has its source in the municipality of Moorgrund, west of Etterwinden on the western slope of the Pfaffenberg. The Suhl then flows through Kupfersuhl, Ettenhausen an der Suhl, where it is crossed by the Werra railway, and the Lindigshof to Marksuhl. Between Ettenhausen and Lindigshof, the Suhl is dammed up in the Ettenhausen dam, which was built at the end of the 1980s.