When describing glaciers in Wrangell St. Elias National Park and Preserve in Alaska, superlatives are hard to avoid. Within our largest national park exists the nation’s largest glacial system, with rivers of ice flowing dozens of miles through majestic mountains. In summer, runoff from glaciers swells rivers and precipitates an explosion of green. From the ground and the air, it’s an epic sight. Photo by Neal Herbert, National Park Service.