There are 26 stunning glaciers in this park on the border between Montana and Canada, including the 410-acre Harrison Glacier, the largest formation in the protected wilderness, and Many Glacier, a key destination for avid hikers. Unfortunately, rising global temperatures mean that number is far less than the 150 glaciers found here at the end of the 19th century. How to visit: In addition to the park’s environmental management plan, the National Park Service suggests visitors walk or cycle through the park where possible, use the free shuttle over their own vehicles and use reusable or recyclable materials during their stay to reduce their effect on the delicate environment.