Experience Gold Rush history in Skagway on the White Pass & Yukon Route Railroad or the Chilkoot Trail. Visit Hubbard Glacier, the longest glacier in the world at approximately 76 miles long. It takes about 400 years for ice to travel the full length of the glacier. While you're on the water, watch out for sea life. The cold, nutrient-rich water in Alaska provides ideal food for humpback whales, orcas, Stellar sea lions, Dall porpoises, harbor seals, sea otters, eagles, puffins and more!