It is located on the northern bank of theEider river, approximately eight kilometers away from its mouth at theNorth Sea. Tönning has a population of some 5,000 people.
Friedrich Wilhelm Selck (1821–1911), councilor of commerce, honorary citizen since 1899
Friedrich von Esmarch (1823–1908), German physician and the founder of the civilian Samaritan system in Germany, honorary citizen since 1897; there is a memorial statue dedicated to him in the castle park.