Honest truth about ice cave tours – their formation and how we find them

A mesmerizing image of crystal clear blue ice forming large caverns, long and deep tunnels or perfectly round arches – all of them shortly but not necessarily always correctly called ice caves – has in the last years become one of the winter symbols of Iceland, almost as popular and important as the northern lights. I bet those 2 things were actually the first ones which you found when you asked your web browser about Iceland’s winter attractions and there are some really good reasons why they act like magnets for tens of thousands of visitors every year. Not only are they both usually extremely photogenic and hence attract photographers from all over the world, the fully professional ones as well as the completely amateur, but also, or perhaps first of all, when someone sees them for the first time, they just seem out of this world. I can’t even count how many times I heard my guests call Iceland “another planet”, but it never happens as often as in winter when they enter their first ever ice cave. In fact I still remember clearly the feeling of amazement and disbelief I had when I visited my first ice cave in 2013 and even though I have done it several hundred times since then, this is something I will never forget. But ice caves have more in common with northern lights than most people imagine – they are similarly elusive and never really appear the same on two different days. How can this be when the glacial ice looks and feels so solid when you touch it or walk on it? The answer is: every part of the glacier undergoes constant changes which never really stop. They might be too slow to notice with a naked eye but over a longer time they become extremely significant. Therefore any formations found in the glacier will always be temporary and rather short lived. This applies to ice caves more than to anything else. That ice cave in 2013 which was “my first” doesn’t exist any more. In fact it was already gone a few months later and in 2014 completely different caves were being visited. As I’m writing it now, in July 2026 also the ice cave which we were visiting on a daily basis last winter ceased to exist. This process of constant change is part of the nature of the glaciers and for us who turned passion towards glaciers into a profession it is one of the most important factors affecting our work. Yet as obvious as it seems to glacier guides or geologists it is usually almost completely unknown to our regular guests. That’s why I will try to explain it in more detail.

Sapphire Ice Cave, March 2020

To start with I need to explain what an ice cave really is. It has to be noted that this is by no means a geological definition, but rather a traditional naming by glacier guides and local people in Iceland who live close to the glaciers. Here the term “ice cave” is used to describe any empty space under part of the glacier which is big enough for a person to get into. The vast majority of ice caves exist right on the edge of the glacier and are formed and shaped predominantly by water and wind erosion. In the most classic scenario a stream of water running under the glacier carves a tunnel which over time gets bigger and wider. The river escapes the glacier somewhere at its terminus (the front part) where the exit of such a tunnel is formed. It is important to note that the flow of water on the glacier and underneath is directly connected to the air temperature and the amount of rain, therefore it changes very quickly. In summer months we expect a high water flow, which in turn disappears almost completely in winter, when it gets cold and dry. Although ice caves can be formed gradually over a longer time, often the biggest changes happen rather rapidly due to a sudden flooding event – autumn rainstorms are the best example here. Once the water is gone from an ice cave the wind becomes the dominant factor eroding and shaping the ice. 

To put it short we could then say that a glacier ice cave is any tunnel formed under the glacier by a sub-glacial river. However other glacial features, often smaller or located within the glacier rather than under it have also been often called ice caves. On the surface of the glacier the water also runs in streams and small rivers, which sometimes find a way down into the ice forming deep glacial wells – so called moulins. At the bottom of a moulin the water continues to run and carve the ice usually in a zigzagging way, so a tunnel can be formed. This means that unlike in previously described ice caves where the ice is only on top and the bottom of the cave is made of rocks and gravel, here the ice surrounds the stream from all sides. Such tunnels are usually very narrow, but can have really tall ice walls on both sides as the water constantly cuts its channel deeper. 

Blue tunnel called “Bellissimo”, March 2023

According to my definition of an ice cave given above, any small hole in the glacier could technically be called an ice cave, so it really isn’t possible to count them all. Only a few outlet glaciers in Iceland are regularly visited, so many more caves could be lying hidden in remote places and the total number could easily be hundreds. The real question however is – how many and which ice caves are possible to visit and worth it. This number will of course be different in different years and even during the same winter it can change, but it is always pretty low, because a few factors have to come together for us to be able to regularly enter an ice cave with groups. In the order of significance these are:

• Safety – no ice cave should ever be visited if it’s unstable or it poses some other dangers. This is a complicated topic which I will cover in another article.
• Accessibility – If an ice cave is too far away or getting into it requires a lot of technical ropework it might not be possible to visit. Longer hiking tours might allow reaching more remote caves, but this still means only a few kilometers from the glacier’s edge. Some truly remote ice caves can be accessed by a helicopter, but this is only possible for very small private groups and the weather conditions affect it greatly.
• Size – very small ice caves can still be interesting but not enough to become the main attraction
• Appearance – not every ice cave looks bright and blue. In fact a lot of them are rather dark, either due to the lack of light or when the ice is full of volcanic ash (Yes, Icelandic glaciers can be very dirty!). The most beautiful ice caves shown in the pictures online are but a selection of the rare best examples from many years. Finding one like that is every glacier guide’s dream.

Sparkle Ice Cave, November 2024

The biggest and fastest changes on the glacier happen in summer, therefore that’s also when the ice caves change the most. Some tunnels under the glacier get bigger and wider at the same time as others disappear entirely when the ice above them melts away. These two things often happen simultaneously in different parts of the same cave – the entrance disappears while the deeper part gets bigger, brighter and more interesting to visit. As a result the same ice cave can change its appearance completely over a short period of time in summer. Glacier guides like me who explore the glacier all year round have a chance to find an ice cave at pretty much any time and believe me – we’re always looking! However in summer ice caves tend to be the least stable and most filled with water, so the main period when we actively look for them falls at the end of summer – usually in September and October when the temperatures drop and the rain increases. That’s when the structure of the ice quickly gets stronger, ice turns more blue and clearer, the water eventually disappears and all changes slow down. When the winter hits properly the ice cave should stay more or less the same for a few months, strongest and most impressive. Ready to be visited and enjoyed by groups.

I’m sure that after reading this you already understand that visiting the same ice cave in two different seasons is pretty much impossible, but things get a bit more complicated here. An ice cave doesn’t necessarily disappear entirely in summer, but rather changes so much that it usually shows almost no resemblance to the previous winters. When its entrance melts away, its deeper part gets bigger, more open and brighter due to the ice thinning above it. As the whole glacier retreats the ice cave retreats with it, but it remains on the glacier’s edge. However if the water flow changes its course the ice cave will disappear. Technically it can even exist for many years and we’ve had a few examples of those, the best one being Sapphire Ice Cave which lasted from 2019 until 2025 and finally disappeared completely recently. On the other hand other ice caves really existed only for one winter. 

Stellar Ice Cave, December 2023

Ice cave tours have been organised in Iceland for almost 20 years now and this became a big part of tourism here. A few hundred people hold the qualification of a glacier guide and 30 companies including ours have a license to sell and organise glacier and ice cave tours in Vatnajökull National Park. It means that the areas of the glacier which we can visit with tours have all been searched and scouted thoroughly many times in the past and unless a miracle happens the chances of finding an undiscovered ice cave in a new location are considered very low. However the most likely place for a “new” cave to form is where there used to be one in the past. Simply speaking the same river could do it again, so we always follow the water when looking for ice caves. A great example could be the ABC cave (which stands for Amazing Blue Cave) – a particularly beautiful one which formed only in some years in a remote corner of the Breiðamerkurjökull glacier.

Treasure Island Ice Cave, February 2019

Ice caves don’t have any official names. I would say they are too short-lived to be given one. In the past guides who discovered the first ice caves gave them some names to tell them apart which later became an unwritten tradition in the Vatnajökull National Park. Crystal Ice Cave was one of the first such names and that cave was lucky enough to exist more or less in the same area for those few winters when Icelandic tourism was booming the most. It became a golden mark for the whole future ice cave business. It had everything you could wish for – it was big, bright and blue, had a stable and thick roof in winter and was accessible by a 4×4 track leading almost exactly to its entrance. When it was finally gone in 2018 many guiding companies had already named their tours after Crystal Ice Cave and weren’t going to change it even when going to a different place. After all, other ice caves were also crystal-like, so the name still fit.

Sapphire Ice Cave, November 2024

This definitely created confusion when Sapphire Ice Cave was the most popular one, but at least half of the guests thought they were going to the Crystal Ice Cave and most of them never learnt the difference, because Sapphire Cave was also exceptionally beautiful. At the same time various fusions of names which never applied to a particular cave such as Blue Ice Cave or Crystal Blue Ice Cave have also started to be used by marketing teams. Other notable ice caves from the past include:

• Treasure Island Caves – 2 magnificent ice caves which required a long walk and opened almost directly towards the Glacier Lagoon Jökulsárlón
• Waterfall Ice Cave which had a small cascade inside
• Sparkle Cave which was discovered completely unexpectedly in the winter 2024/2025 under a pile of rocks in so-called dead ice – the already separated part of the glacier. It possibly was the biggest ice cave visited regularly on tours.
• Stellar Ice Cave – an extremely remote ice cave in Skeiðarárjökull glacier accessible only by helicopter
• Amazing Blue Cave (ABC) – a beautiful and quite remotely located cave which became a star of the last season 2025/2026, when no other big and blue cave was accessible near the edge of the glacier

ABC Cave, November 2023

Vatnajökull Glacier was the cradle of Icelandic ice cave exploration and tourism, however other ice caves exist and have existed in different glaciers in Iceland as well. Those include:

• Katla Ice Cave which is also a generic name given to any ice cave in the Kötlujökull glacier over the past years. The name Katla refers to a big volcano which is sleeping under the glacier nearby.
• Ice caves in Kverkfjöll – volcanically heated geothermal area under the glacier which forms some of the most unstable and dangerous ice caves in Iceland which can only be observed safely from outside
• Langjökull ice tunnel – an artificially created large ice cave in the upper part of Langjökull glacier which always stays pretty cold. It was originally built for research purposes but became a tourist attraction later. This is the only ice cave which doesn’t really change from year to year.

ABC Cave, November 2023

To put it shortly – every tour is a little different! During one winter season day after day the tours might look similar, but there are always small changes happening to the glacier and if the weather gets extreme then the changes can be quick. There is never a guarantee that a particular ice cave will be good and safe to visit on a given day even if the day before tours have entered it successfully. That being said, usually ice caves do last throughout most of winter and it is in spring and summer that they change drastically or disappear completely. 

The ice cave experience in different winter months also varies. In November and especially October when it hasn’t turned very cold the ice caves might not have stabilized properly yet and some of them may be too dangerous to enter yet, while others still need time to get more blue. December and January are in the dead of winter when the ice is the strongest and the bluest, so it can be considered the best time to visit ice caves if not for often challenging weather conditions. In February the sun starts to shine stronger again and affect the glacier more and by March ice caves are usually already melting a lot and the glacier loses the blue color which remains only in the deeper parts of the caves where the sun doesn’t reach. April is the very end of winter and only the caves well sheltered from the sun will still look blue then. 

When it comes to the tours in Vatnajökull region no-one can tell at the moment which cave and if any will be possible to visit in the upcoming winter. The biggest cave from last year, the ABC is almost completely gone and if a new one forms there it will not be connected to the old tunnel. Any smaller tunnels from the last season have also disappeared, but some new ones can already be seen forming. Only the future will tell how exactly our tours will look like, but you can be sure that we will be always taking you to the most beautiful ice cave available at the given moment. Lastly, there has not been a season in my 10 years of guiding when there wouldn’t be any ice cave there.