Cross-country skiing is a popular way to explore Yellowstone in the winter. NPS/Bianca Klein. Yellowstone has miles of trails for the adventurous skier and snowshoer. Though track is set only on a few trails, all unplowed roads and trails are open to cross-country skiing and snowshoeing. Whether you are skiing a groomed trail in a developed area or venturing into the backcountry, remember that you are traveling in wilderness with all its dangers: unpredictable wildlife, changing weather conditions, hydrothermal areas, deep snow, open streams, and avalanches. Your safety is not guaranteed. Be prepared for any situation and know the limits of your ability.