Norway
Summer's warm weather and long days are perfect for hiking, cycling, or making the most of a 72-hour Oslo stopover (about 58 of which will be spent in broad daylight in mid-June). Winter, though dark (with long nights down south and endless nights up north), is the best time to visit for cold-weather activities like skiing, snowboarding, and ice-climbing—all pursuits either invented by Norwegians or perfected by them. Visitors to Norway's far northern city of Tromsø can experience 24 hours of sunlight for much of the summer, and perpetual and near-perpetual darkness, with a good chance of witnessing the spectacular northern lights, during much of the winter.