What exactly is an ice cave and how is it formed?
All ice caves in Iceland lie within or beneath glaciers. These caves are formed by the meltwater of the glacier that flows through the ice during periods of rainfall or during the warmer months when the glacier ice is melting. Glacier and Volcano Expeditions define an ice cave as a hole on a glacier that a human being can fit inside and have an ice "roof” above their head. This means that a cave can be large enough for one small person to squeeze inside, or it can be so big that an entire freight train could fit in!
All of the glacier ice caves are constantly changing as the glacier melts and moves. The most fascinating part of guiding glaciers and ice caves is having the opportunity to witness these natural processes. However, these natural processes also come with a degree of challenge for all of the ice cave guiding companies, including Glacier and Volcano Expeditions, as the environment that we operate tours within is inconsistent.
There are three types of glacier ice cave:
Subglacial ice caves
Subglacial caves lie right at the very bottom of the glacier so when one enters the cave they will usually be walking beneath the glacier on the rocky bed surface that the glacier lies on. These caves are formed either from water that flows out from beneath the glacier, or from water that flows down beneath the side of the glacier from an external source. Generally subglacial ice caves are only accessible during the colder winter months when there has been low amounts of rainfall.
Surface ice caves
Surface ice caves are usually located at the surface of the glacier and are formed as water and air melts a hole through the ice, melting the glacier on the inside and therefore creating a cave. Surface ice caves can be found on the glacier all year round, however they are very susceptible to melt due to warm air temperatures, sun exposure and rainfall. Surface ice caves tend to generally be smaller in size than the subglacial ice caves but they often provide a more “icy” cave experience as surface ice caves usually consist only of ice, as opposed to the rocky floor of the subglacial ice caves.
The photography potential for surface caves is fantastic as there is generally a lot more light available and the absence of rocks on the floor of the cave can provide a more aesthetically pleasing image.
Compression arches
Compression arches are caves that are formed due to surface tension on the glacier as the ice is compressed beneath an icefall. The result is an arch with a similar structure to a bridge. Compression arches can be found at any time of the year on the steeper glaciers. Compression arches are a very intriguing glacial formation and it is always interesting to pay them a visit.