One central bank cannot undertake the responsibility for two different currencies. Similarly, two central banks cannot undertake the responsibility for one currency. 2. Currencies in the North Atlantic region  According to these criteria Iceland evidently has its own currency, the Icelandic króna, and its own central bank, Sedlabanki Íslands. The currency is associated with the country of Iceland.
Denmark, the Faroe Islands and Greenland employ the same currency, the Danish krone. Danmarks Nationalbank is responsible for this currency. Let us look at the use of Danish kroner within the Danish Commonwealth in the light of the five criteria. Re 1) Danish kroner are available as banknotes and coins and can be used in the entire area.