| Südermarsch Sønder Marsk | |
| Image Coa: | kein |
| Coordinates: | 54.4167°N 13°W |
| Image Plan: | Suedermarsch in NF.PNG |
| State: | Schleswig-Holstein |
| District: | Nordfriesland |
| Amt: | Nordsee-Treene |
| Elevation: | 0 |
| Area: | 30.66 |
| Postal Code: | 25813 |
| Area Code: | 04841 |
| Licence: | NF |
| Gemeindeschlüssel: | 01 0 54 132 |
| Mayor: | Karl-Jochen Maas |
Südermarsch (Danish: Sønder Marsk[1]) is a municipality in the district of Nordfriesland, in Schleswig-Holstein, Germany.