* There is no island nation southwest of Greenland, which is the location of Canada.
The island nation southeast of Greenland is Iceland, whose capital is Reykjavik.
Iqaluit is the territorial capital and the largest community of the Canadian province of Nunavut, which is west of Greenland. Ottawa is the national capital of Canada, and Nunavut is part of Canada.
The island southwest of Japan and east of China is Taiwan, whose capital is Taipei.
Baffin Island is probably the largest near Greenland.
Greenland is a dependency of Denmark
Denmark
Iceland.
Greenland is the island nation located in North West of Iceland.
Greenland
Depends on the island nation you are asking about. The island nation of Great Britain's capital is London. The island nation of Cuba's capital is Havana. There are dozens more. http://en.wikipedia.org/wiki/List_of_island_countries
The largest island in the world is Greenland with a total area of 839,999 square miles. After that comes New Guinea, Borneo, Madagascar, and Baffin.
Cairo is the capital and largest city of Egypt, which is not an island nation.
The nation's capital, Washington D.C., is located in the northeast region of the United States. It is not in either the southeast or southwest regions.
The capital of any nation (island or otherwise) is the city where the national government is headquartered.