Mors or Morsø is an island in the shallow sound called Limfjorden within Denmark's Jutland peninsula. It has an area of 367.3 km2 and as of 1 January 2019, it had a population of 20,373. The main town on the island is called Nykøbing Mors. Geologically Mors is unique. Like the neighbouring island of Fur, it is known for its deposits of diatomite, locally known as 'moler' (mo-clay).