Matanuska Glacier Ice Caves

Caves belong to winter

The ice caves on the Matanuska are made by water and opened by cold. All summer, meltwater runs across and through the glacier, carving channels into the weaker parts of the ice. Once the temperature stays below freezing for weeks, those channels drain and harden. The operator at the park gate puts the point where the ice turns solid at around mid-November, and says the caves are really only accessible in the winter. On rare occasions a cave is safe to enter in summer, but you cannot plan a trip around that.

So the season for ice caves is the park’s winter season, which runs from 15 November to 14 April, give or take two weeks either side for the weather. Within that, December through March is the most dependable stretch: the ice has had time to firm up, and the spring thaw has not started.

Why no tour can promise a cave

Every cave is temporary. The local tourism office warns that they can disappear or become unsafe in a matter of days, and one operator in the valley puts it more plainly: some last for years, some for months, some are gone within the week. A cave that was on every photograph in January can be closed by February.

That is why the honest tour listings are careful with their wording. The park’s own operator promises white ice on every trip and says caves are shown when accessible. The Anchorage day tours on this page do not name caves in their itineraries at all. What they do is put you on the ice with a guide during the months when caves exist, and the guides take the group into one when there is a safe one to visit. If no cave is stable that week, you still see the same deep blue in crevasse walls and ice formations.

Treat anyone who guarantees a Matanuska ice cave on a specific date with some caution.

Never go in without a guide

Access to the ice at the Matanuska is through the privately owned park, and it is guided only. That rule matters most around caves. Guides read the ice, check overhead for loose sections, and decide each day which features are safe. The tourism office’s advice is short: never enter an ice cave without a professional, certified guide. Nobody who has watched a cave ceiling in a thaw would argue with it.

Why the ice is so blue

The colour is real and not a filter. Glacier ice turns blue when it has been compressed so hard that the air bubbles are squeezed out. Dense, bubble-free ice absorbs a little of the red end of the light that passes through it, so what reaches your eye is blue. Inside a cave, the light has come through a thick wall of that ice before it reaches you, which is why the walls glow in a way the surface never does. White ice looks white because its bubbles scatter the light before much of the red is absorbed.

Which tours go onto the ice in cave season

From Anchorage: Matanuska Glacier Winter Tour with Lunch is the one we would book for a cave-season visit. Greatland Adventures built it for winter, with hotel pickup from select Anchorage hotels, all glacier equipment, lunch, snacks and water, and a hot meal at a local eatery at the end of the eight-hour day. It is rated 5.0 out of 5 from 16 reviews on GetYourGuide, and the listing’s own photographs are of guests inside blue ice. One cost to budget for: the operator rents a winter gear package of parka, snow pants, boots, hat and gloves for $30 if you have not brought your own. The same winter tour has a much larger review base on Viator:

From Anchorage: Matanuska Glacier Full-Day Tour is the choice if the walking worries you. From late November to April, 907 Tours takes guests out to the blue ice on sleds towed behind a snow machine, driven by the operator, so the approach is a ride. It is ten hours with all entry fees included, and rated 4.8 out of 5 from 118 reviews. Our sled tours guide explains how that works.

Anchorage: Matanuska Glacier Hike with Transfers picks up from your hotel or Airbnb and hands out gloves and snow pants with the safety gear, which helps if you have flown in without winter clothing. It runs year-round, about eight hours door to door, rated 4.8 out of 5 from 36 reviews.

If you have a car, the park’s own operator at Mile 102 runs guided tours every day of the winter, leaving at 10am, 11am, 1pm and 2pm, for about $150 per adult with the gate fee included. Its pages quote slightly different prices, so confirm before you drive up. In the valley, MICA Guides also runs winter helicopter trips from October to May that include exploring an ice cave; those are a separate and more expensive kind of trip, flown rather than driven.

The best months for caves

December has the shortest days of the year, only five and a half hours of sunlight in Anchorage around the solstice. The caves are open, the glacier is quiet, and the low light makes the blue deeper, but you will drive part of the way in the dark. Our December guide covers that.

January is the coldest month, with Anchorage averaging a low of 11°F (−11.7°C). The ice is at its firmest and the crowds are at their thinnest.

February and March bring the light back fast, gaining more than five minutes a day. By mid-March Anchorage has close to twelve hours of sunlight while the caves are still in winter condition, and that combination makes March the easiest month for a first cave visit. See our March guide.

November is the gamble. The ice is still firming up in the first half of the month, and the park’s winter season only begins on 15 November, so caves may not be open yet. Our November guide goes through the changeover.

What to wear inside the ice

Caves are colder and damper than the open glacier, and you will brush against walls and crouch under low ceilings. Wear a waterproof outer layer over warm insulation, waterproof winter boots with a stiff sole, gloves you can grip with, a hat that fits under a helmet, and a buff or scarf for the wind outside. The park’s own winter list adds wool socks and sunglasses. Everything else is in our what to wear guide.

Photographs in a cave

Phone cameras handle the blue well, but the cold drains batteries quickly, so keep a spare phone or power bank in an inside pocket. Turn off the flash, because it flattens the colour. The best pictures come from standing near the entrance with the light behind the ice, not from the darkest part of the cave.

When you have picked your month, check availability for the winter tour.