Of the 20 highest peaks in the United States, 17 are in Alaska. Denali, the highest peak in North America, is 20,320 ft. above sea level. Denali, the Indian name for the peak, means "The Great One."The Yukon River, almost 2,000 miles long, is the third longest river in the U.S. There are more than 3,000 rivers in Alaska and over 3 million lakes. The largest, Lake Iliamna, encompasses over 1,000 square miles.Alaska has an estimated 100,000 glaciers, ranging from tiny cirque glaciers to huge valley glaciers.Alaska has 6,640 miles of coastline and, including islands, has 33,904 miles of shoreline.There are more than 70 potentially active volcanoes in Alaska. Several have erupted in recent times.