Sassnitz (German pronunciation: [ˈzasnɪts]) (before 1993 in German: Saßnitz) is a town on the Jasmund peninsula, Rügen Island, in the Federal State of Mecklenburg-Vorpommern, Germany. The population as of 2007 was 10,747.

It is a well-known resort town, and is a gateway to the nearby Jasmund National Park. Sassnitz is home of Rügen's only zoo, the Sassnitz Wildlife Park. The decommissioned British submarine HMS Otus was purchased by a German entrepreneur and towed to Sassnitz to be a floating museum. Sassnitz area is most popular for its famous chalk rocks which inspired artists as Caspar David Friedrich.

The borough of Sassnitz lies in the northeastern part of the island of Rügen, covering the eastern part of the Jasmund peninsula as far as the sand bar of Schmale Heide to the south. The countryside here is renowned especially for its chalk cliffs. In addition, ice age depositions dominate the landscape. Its depressions have frequently been filled by small lakes. The most striking chalk cliff is the 118 metre-high Königsstuhl. Large parts of the borough are covered by various types of wood with their typical habitats. One feature is the forest on the coastal slopes. Here there are rare trees like wild pear, wild apple and yew. The town liies on the coastal slopes at the southern end of the Stubnitz, a 7.5 kilometre-long and up to four-kilometre-wide beech forest. The remaining land areas consist of moors, beach, meadows, pastureland and settlements. In the south of the borough, near Mukran, are the Wostevitz ponds, a boggy depression that is protected as a nature reserve. The small stream of Steinbach flows through the built-up area of the town.