Regarding Oslo: - If you can, take one of the ferries to Hovedøya, one of the small islands in the fjord. The time you're there is great for swimming. (And you can say you've been swimming in Oslo fjord.) These ferries hop several islands and head back to mainland Oslo, right in front of Town Hall. Bring a disposable bbq/grill and go native - You might want to take the T-bane up to Frognerseteren. The ride up (sit on the left side when facing forward) gives you a very nice view of Oslo. Also, the surroundings are absolutely stunning when up there. Out of the urban, and right into nature. The blueberries (blåbær) might just about start to ripen at that moment, and they are everywhere up there. - And if you're into that kind of thing, check out Helvete/Neseblod record store. A central place in the early Norwegian Black Metal scene.