Welcome to Fluther.
I doubt that “everything” is two to three times more expensive in Norway, but to the extent that the claim is true, some fundamental factors apply:
1. The devaluation of your own country’s currency vis-a-vis the Euro, and
2. A lot of the things that you’re used to in your country (whatever country that is, and whatever things you’re used to buying regularly) are imported into Norway. That importation costs money in terms of added transportation cost (generally pretty modest, unless you move north of the Arctic Circle, as @Blackberry‘s post suggests), and added tariff if the product isn’t imported from Europe.
3. Norway, for all of the good things about it, is like much of the rest of Europe in that it heavily taxes income earners and corporations in order to fund very generous social programs. That money has to come from somewhere, so it’s reflected in the cost of goods and services that are offered for sale. It also applies to the wages that people earn.
Some things (such as gasoline / petrol) are taxed much more heavily than the United States (which has some of the lowest fuel taxes in the world) in order to subsidize things like rail travel. You might be surprised to see how little a train ticket costs, for example. (This is why I doubt your claim that “everything” is so much more expensive.)
Finally, one of the things that makes Norway a relatively prosperous country now (it hasn’t always been!) is the North Sea oil deposits that it manages with a state-owned oil company that returns most of its dividends to Norwegian citizens. So, since their incomes have improved, enabling increased demand for goods and services, the cost of those goods and services have also grown, as a direct reflection of expected supply-and-demand curves.
Keep in mind that part of its attractiveness is its apparent prosperity. There is a lot less tourist travel among impoverished regions of the world.