Iceland is home to some of the most striking natural landscapes in the world, from volcanoes to ice caves and all in between. Mesmerising glaciers grace its territory, which, during winter allow the formation of a whole underworld of ice sculptures, winding tunnels, and breath-taking sceneries all of which can be seen by joining a guided ice cave tour.
Want to learn more about Ice Caves in Iceland? Discover why they are blue in colour and step into Vatnajökull’s magical underworld? If so, then read on.
What is the difference between Ice Caves and Glacier Caves?
The similarity in the names of the two types of caves can be rather confusing. Both in verbal communication and on tourist websites, Glacier Ice Caves are often referred to as “Ice Caves”, even though this name is usually given to the year-round ice-covered rock caves.
Glacier Ice Caves are indeed also “icy” because they are freezing cold and dense droplets of ice water, often accompanied by rock debris and other pieces, continually breaking off the cave’s roof, falling into the interior.
But Ice Caves and Glacier Caves are different creations. At the very least, they differ in colour: some of the Glacier Caves, but far from all, are blue; they are accessible between mid-October and late March, while tours to the Ice Caves are recommended starting in November. The color of the ice varies and can be blue, white, grey, or black.
How were the caves shaped?
Most Glacier Caves are formed initially by water flowing through or under the glacier, which usually leaves the glacier’s surface after melting, enters the ice through fissures and crevasses, and exits at the glacier’s snout. They are formed by the melting of the ice at the glacier’s end over a prolonged period of time, combined with the gradual formation of a small cave between the glacier’s base and the ice mass that has formed on top of it.
Moving water, if present inside the glacier, can also form cave spaces. So both the caves and the network of tunnels found under glaciers are the creation of sunlight and water melting at the heart of the ice formation. Very few are the result of human activity.
Why do they appear blue in colour?
As the ice slips over the edges of the glacier over the centuries, it pushes out little air bubbles that become a stable piece of icy flesh. Having pushed the air out completely, the ice becomes particularly dense and begins to absorb visible light continuously and completely, leaving only the blue spectrum free to the ordinary human eye.
Due to the absence of air bubbles, the light enters further in and absorbs even more of the dark shade. This is why the color of glacial caves is deep blue, unlike their sisters, the ice caves, which are reddish, or even black.
At what time during the year can you visit the caves?
The glacier caves are only safe to visit in winter when cold temperatures harden the ice, but even then, caution should be exercised. The season runs from November to March although tours are also organized in October as well as the first half of April. Because parts of the glaciers melt each summer and re-form in autumn and winter, the caves offer an ever-changing picture that is continuously dissimilar. As they melt, they become deep lakes from which water evaporates in summer and turns into clouds.
These clouds begin to ‘rain’ in the autumn and the snow re-crystallises into glaciers. You can visit all year round the cave under the Katla volcano and the man-made cave at Langjökull glacier. You might think that inside the cave the environment is quiet and tranquil, but in reality, it is quite the opposite: there are constant noises, big bangs and ice fall-off as it moves alongside the movements of the glacier itself. Every time the glacier moves even one millimetre, visitors inside the cave can be startled by loud creaking sounds of crumbling rocks and new crevasses emerging.
All of Iceland’s Ice Caves are only accessible in the presence of a qualified guide. Should you wish to fully immerse yourself in Iceland’s winter wonderland, why not take a look at our 5-Day Winter Guided Tour that includes an Ice Cave Tour and much more!
What are the most popular ice caves in Iceland?
Vatnajökull Glacier Ice Caves
Vatnajökull glacier in the southeastern part of the island is the largest in Europe by volume and the 3rd largest in the world, after the glaciers of Antarctica and Greenland. It is a sloping ice dome rising from 600 meters to 2000 meters. There are several volcanoes below the glacier, a common occurrence in Iceland.
Eruptions of ice volcanoes are usually accompanied by intense ice melt, causing catastrophic flooding. Some of its southern branches descend almost to the coast. There is a huge crater in the Vatnajökull glacier and a 488 m deep lake. The lake is covered with an ice sheet about 200 m thick. It is warmed from below by the hot waters of the lake and some of it melts.
The water from the melted ice occupies a larger volume than the ice and periodically breaks out from under the ice cap. This powerful outburst, called in Icelandic Jökulhlaup, sweeps everything in its path, including ice blocks over 20 meters high.
Crystal Ice Cave
The tunnels and passages beneath the glacier create one of the country’s most visited Ice caves named The Anaconda Ice Cave or the Crystal Ice Cave. Both names are given to this spectacular natural wonder due to its distinct crystal blue color and many twisting tunnels found inside. Its strikingly transparent ceiling gives it an even bluer hue, adding to the already stunning setting!
Blue Diamond Ice cave
Oftentimes mistaken for the Crystal Ice Cave, this blue ice cave found in the winter of 2016 had many names associated with it. Some named it the Sapphire Ice Cave, others called it the Blue Ice cave simply because well… its transparent blue colour. Found yet again on the Vatnajökull glacier, the Blue Diamond Ice Cave was often visited when weather conditions at the Crystal Ice Cave deteriorated.
It was home to an abundance of naturally carved ice tunnels idyllically harmonising with a plethora of textures and colours and was only reachable during the winter months by a short super truck drive from Jökulsárlón glacier lagoon followed by a guided glacier hike. Although it was much smaller than the Crystal Ice cave and could only comfortably fit around 15 people at a time, the Blue Diamond Ice Cave was considered to be of better colouring.
Visitors could also visit a nearby Black Diamond Ice Cave, renowned for its dark colours and charcoal tunnels. As of 2022, both the Blue Diamond and Black Diamond Ice Caves have disappeared and it is not known when or if they will ever reappear once again.
Waterfall Ice Cave
Discovered in the winter of 2015-2016, the waterfall Ice cave, had a small river and, as its name suggests, a beautiful waterfall running all across it. Although its entrance wasn’t of vast size, a few steps further along the river opened to a much bigger space with different hues of blue all around. The cave itself was only accessible for two winters in a row, before being naturally destroyed in 2017.
Kverkfjöll Cave is extremely hidden and access to it is often difficult if not impossible. It is formed entirely by geothermal activity beneath the earth’s crust. Set on the north side of Vatnajökull, Kverkfjöll is divided into two parts: Hveradalur (the upper ice caves) and Jökulsá á Fjöllum (the lower ice caves). Something really special happens in this cave system: under the glacial ice, you can see a river of hot water running through the cave, forming its exclusivity.
On the outskirts of Skaftafell National Park, you will find the entrance to Svínafellsjökull Cave. It is the site of a phenomenon called ‘glacier milling’, where rain and meltwater on the glacier surface are directed into streams that enter the glaciers through crevasses. The resulting waterfall melts a hole in the glacier while the floodwater drains to lower elevations, forming long ice caves with an outlet at the end of the glacier.
Due to the glacier’s rapid movement of about 1 m per day across uneven terrain, this ice cave has cracked, creating a deep vertical fissure called a serac. This causes indirect daylight to enter the ice cave from both ends, resulting in homogeneous illumination of the ice tunnel. The cave is accessed through a 10-metre-long tunnel.
Katla Glacier Cave
The cave is found under the mighty Katla volcano of the same name. This 800-year-old cave is much closer to Reykjavík, about a two-hour drive, and is distinguished for its unusual black colour. Legend has it that Katla, a cook at a nearby monastery who was noted for her short temper and penchant for witchcraft, gave its name.
Of all the caves on this list, Katla is the only one that can be visited year-round. The few glacial caves are small, and access to the interior of the cave is by short multi-colored tunnels, which you most likely would need to crawl to get inside.
Langjökull glacier cave
Langjökull is Iceland’s second-largest glacier with a dimension of just under 950 square kilometres. Its name comes from its oval shape – the “Long Glacier”. It can be visited both as a natural cave and a man-made ice tunnel. The ice cave has a rather spectacular coloring to it: the natural cave is black with the ice ceiling covered with ash.
Iceland’s ice caves have formed a network of tunnels that stretch for a distance of about 300 metres and are usually 30 metres below the surface of the ground. They can also be seen in summer, so a visit to them is recommended. Caves are also created artificially by tunnelling. The tunnels are high up in the glacier, unlike natural ice caves, which are usually located on its edges and are therefore very unstable. Because of their location, the tunnels are stable and accessible all year round.
One such man-made cave was opened to visitors in 2015 at Langjökull Glacier. It was created from hundreds of metres of man-made tunnels and five separate chambers carved into the ice, with a maximum depth of 300 metres below the surface. There is even a chapel among these impressive tunnels. Concerts are held in them, including the ever so famous Secret Solstice Festival.
With over 14% of Iceland’s surface covered in glaciers and lakes, it makes for the perfect opportunity to explore a plethora of ice caves, both natural and man-made. Although their shape, size as well as coloring varies greatly, one thing is for sure, whichever ice cave you choose to explore, you certainly will not be left disappointed!