Kenai Fjords National Park and Prince William Sound are home to some of the most magnificent glaciers in Alaska. The Harding Icefield in Kenai Fjords National Park covers more than 700 square miles and is the source of over 35 named glaciers. Contained by 3,800 miles of coastline, Prince William Sound is home to 150 glaciers, including 17 tidewater glaciers. Several different types of glaciers can be seen from our cruises, including tidewater, piedmont, hanging, and cirque glaciers.
HOW A GLACIER IS FORMED
The three main ingredients in the formation of a glacier are time, snow, and cool summers. The Gulf of Alaska sends lots of moisture to Southcentral Alaska, giving the Harding Icefield, for example, an average of 60 feet of snowfall every winter. Glacial ice forms relatively quickly in Alaska, in just four to ten years. When snow first falls, it is about 80% air. As time passes and that snow received additional snowfall on top of it, more and more air is compressed out. Once the snow has compacted to a point where it is only 50% air, it may still look like snow but it’s called firn, part of a process called firnification. Given more time and more snowfall, the snowpack will reduce to 20% air, and at that point it has become glacial ice.
WHY IS THE ICE BLUE?
One of the most common questions about glaciers that we get on our cruises is: why is the ice blue? White light includes a spectrum of different wavelengths that are represented by all colors of the rainbow. When light hits denser ice, the denser ice absorbs all colors of the wavelengths except the shorter, high-energy blue wavelength. The blue wavelength is reflected back, making the ice appear blue.
BEST CRUISE OPTIONS FOR GLACIER VIEWING
PRINCE WILLIAM SOUND
Blackstone Bay Glacier Cruise
Glacier viewing: two tidewater glaciers, one hanging glacier, and nine cirque glaciers
This cruise spends the most time in front of glaciers of all of our cruises.
KENAI FJORDS NATIONAL PARK
8.5 Hour Northwestern Fjord Cruise
Glacier Viewing: 3 tidewater glaciers, one piedmont glacier, and many cirque glaciers
7.5 Hour Kenai Fjords National Park Cruise
Glacier Viewing: 2 tidewater glaciers, one piedmont glacier, and many cirque glaciers
A tidewater glacier occupies a fjord and terminates in the ocean. The terminus lies below sea level and generally has an almost vertical face (often over 1,000 feet high) that sheds off huge chunks of glacial ice. This spectacular display, called calving, can vary dramatically throughout the year.
Kenai Fjords: Holgate Glacier, Aialik Glacier, Northwestern Glacier
Prince William Sound: Blackstone Glacier, Beloit Glacier, Surprise Glacier
A piedmont glacier is a broad valley glacier that terminates on an open slope or plain beyond the mountains. Piedmont glaciers recede and create dry outwash plains or freshwater lakes at their termini.
Kenai Fjords: Bear Glacier
Hanging glaciers flow down out of mountain valleys and are generally larger at the head and smaller at the base. The terminus of a hanging glacier lies above sea level.
Kenai Fjords: Godwin Glacier, Porcupine Glacier
Prince William Sound: Northland Glacier, Whittier Glacier, Billings Glacier
A cirque glacier is a small glacier that occupies a bowl-shaped depression between mountain valleys. They are generally small and circular or oval in shape. There are many cirque glaciers throughout the area, most of them unnamed.
Kenai Fjords: Porcupine Glacier, Spoon Glacier, Prospect Glacier