Alaska holds the largest concentration of glacier ice in the United States, defined by its massive, flowing rivers of ice. Glaciers cover a substantial portion of the state, shaping the landscape and playing a significant role in its ecology and geography. This immense volume of ice is spread across nearly 75,000 square kilometers, an area equivalent to about five percent of Alaska’s landmass. This glacial coverage is more than 100 times the amount found in the rest of the country combined.
The Immense Scale and Diverse Types of Alaskan Glaciers
The number of glaciers in Alaska is difficult to quantify precisely, with estimates ranging from 27,000 mapped glaciers to over 100,000 when including smaller, unnamed ice masses. Only about 600 have been officially named by the U.S. Board on Geographic Names. These ice structures take on distinct physical forms based on the topography they occupy.
The most common form is the Valley Glacier, which is constrained by mountainsides and flows down valleys. When a valley glacier extends to the ocean, it becomes a Tidewater Glacier, such as those in Glacier Bay. Tidewater glaciers actively calve large icebergs into the sea, and Alaska is home to about 60 active and former examples.
A third major type is the Icefield, a vast expanse of ice where the flow is influenced by the underlying mountain topography. The Harding Icefield in Kenai Fjords National Park is a prominent example, serving as the source for numerous individual glaciers that flow outward. Other formations include Piedmont Glaciers, which spill out of a mountain valley and spread into a wide lobe on a flat plain, and smaller Hanging Glaciers clinging to steep cliffsides.
Geographical Concentration of Glacial Regions
The greatest concentrations of Alaska’s glaciers are found in the high-elevation, moisture-rich mountain ranges along the southern coast and interior. Southeast Alaska is home to the expansive Coast Mountains, where famous glacial retreat and calving activity occurs in Glacier Bay National Park and Preserve. This region features numerous tidewater glaciers that descend directly into the fjords.
Moving north, Southcentral Alaska contains two heavily glacierized areas: the Chugach Mountains and the Kenai Mountains. The Chugach range, which borders Prince William Sound, is home to the Columbia Glacier and the Knik Glacier. The Kenai Peninsula features the Harding Icefield, which feeds over 40 named outflow glaciers into the Kenai Fjords National Park.
Further inland, the Alaska Range contains the highest peaks, including Denali, which is surrounded by hundreds of glaciers. Long, continental glaciers flow down the slopes of these mountains, with notable examples like the Ruth Glacier and the Kahiltna Glacier carving deep valleys.
Practical Ways to View Glaciers
The primary methods for observing these ice masses involve water, air, or road access. Water access is the most popular way to see tidewater glaciers, with boat tours and cruise ships operating in Prince William Sound and Kenai Fjords National Park. These tours allow visitors to witness calving, where chunks of ice break off the glacier face and fall into the ocean.
For remote views, Air Access via flightseeing tours provides an unparalleled perspective over icefields and mountain ranges. Departing from hubs like Anchorage or Talkeetna, small planes or helicopters fly over the Knik Icefield or the Alaska Range, sometimes offering glacier landings. These aerial excursions are the best way to appreciate the scale of the high-altitude glacial systems.
Several glaciers are accessible by the state’s limited Road Access network, offering a direct, self-guided experience. The Matanuska Glacier, a large valley glacier, is located off the Glenn Highway and is the largest glacier reachable by vehicle in the United States. Exit Glacier, near Seward, is the only section of Kenai Fjords National Park that can be reached by road, allowing for easy hiking to the glacier’s terminus.