Alaska's winter days may be a little shorter than summer's endless daylight, but they're full of beauty, with fresh snow everywhere and long twilight hours that paint the sky and the mountains in shades of pink, purple and orange. After a cold spell, the trees are covered in a magical-looking layer of thick, crystalline hoarfrost, and once darkness falls, you might see the ethereal northern lights dancing overhead. Winter sightseeing tours in Alaska offer a once-in-a-lifetime experience: You can ski, snowshoe or even ride a snowmachine into the backcountry, take a flightseeing trip to see Denali's glaciers and ice fields cast into stark relief or indulge in some of the best pulse-pounding heli-skiing in the world. Alaska’s most popular winter sightseeing option, by far, is northern lights viewing. Several businesses cater to this niche with aurora-themed tour options, including trips north of the Arctic Circle for some of the most dramatic displays.