Skiing in Greenland. Minerals, strategic military bases. Small, but good veggies, and cattle. I would imagine the fishing industry would be good also.
Technically, Australia is an island. But is so large it is also considered a continent. Sometimes, it is called an “island-continent”...I think the last description is best. IMHO
Skiing in Greenland.
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Be sure to pack a rifle of large handgun for when you meet the island’s resident polar bears.