Northern Loop Trail runs 25 mi. from Carbon River to Sunrise. It climbs through rugged Windy Gap, intersects with a trail leading to Natural Bridge and passes Lake James, Grand and Berkeley parks and Frozen Lake. Combining the section of the Wonderland Trail from Sunrise past Mystic Lake and the Winthrop Glacier makes for a challenging 42.5-mile loop back to Carbon River. The trail is free of snow only from late July to mid-September.