Langjokull Glacier Facts

Langjökull is Iceland's second-largest glacier, and second place is narrower than almost anybody realises. The figures below are the ones the Icelandic bodies that measure them actually publish, with the source named beside each. Where a number could not be confirmed it is listed at the foot as unconfirmed rather than rounded into the text.

820 square kilometres, and second place by 25

Náttúrufræðistofnun Íslands, the Icelandic Institute of Natural History, puts Langjökull at 820 km² in 2023. Vatnajökull, the largest by a distance, is 7,600 km². Hofsjökull, the third, is 795 km².

Second and third are therefore twenty-five square kilometres apart. That is a small margin on a body of ice that has been losing volume for a century and a quarter. It is why a figure written in 2015 may not hold in 2035. The two glaciers face each other across the Kjölur route, and on a clear day you can see one from the other.

Sixty-six metres of ice, gone since 1890

Researchers at the University of Iceland's Institute of Earth Sciences, working with the Icelandic Meteorological Office, measured the change across the whole of the country's ice. Between 1890 and 2019 Langjökull thinned by about 66 metres and lost about 29 per cent of its volume.

Set that against the national figure and it stands out. Icelandic glaciers as a whole have lost almost 16 per cent of their volume over the same period, and the country's ice has shed close to 10 gigatonnes a year since 1994. Langjökull is losing ground faster than the average. That is what a relatively thin, relatively low, southerly ice cap does.

1,260 metres above the sea, and about 0 °C inside

The tunnel driven into the ice cap has its entrance at around 1,260 metres above sea level, and the operator gives the temperature inside as around 0 °C. Walking it takes about an hour on level ground, with crampons handed out at the door.

That temperature inverts what people expect. In January the air on the surface is well below freezing, and the wind makes it colder still. Inside the tunnel it is at the melting point of ice, with no wind at all. The coldest part of a winter ice cave tour is the walk from the truck.

What the name means, and what the map calls the parts

Langjökull is Icelandic for "long glacier", and the name is a description rather than a legend. The ice cap runs roughly fifty kilometres north to south and is far narrower than it is long. Nothing about it is dramatic in profile. It is a low white dome on a flat highland, which is exactly why vehicles can drive on it and why a tunnel could be cut into it.

The two roads that reach it carry names travellers meet before they meet the glacier. Kaldidalur lies on the west side: the "cold valley" between Langjökull and Ók. Kjölur lies on the east, the "keel" running between this ice cap and Hofsjökull.

The water that leaves the glacier

Meltwater off the southern end of the ice cap feeds the river system that produces Gullfoss. That is the practical reason the Golden Circle and a glacier day sit so naturally in one itinerary: the waterfall and the ice are the same water an hour apart. The rivers off the western flank cut the braided gravel plains the road to Húsafell crosses.

It is also why a warm summer changes the look of the day rather than cancelling it. More melt means more water in the rivers and more grey in the ice, and the snowline retreats up the cap. But the surface at 1,200 metres holds snow through August, which is why snowmobiling runs all year.

Three widely repeated figures that no authority publishes

Three numbers about Langjökull circulate everywhere. None of the three is published by a body that measures the glacier, so none of them is stated above.

• The summit elevation. A height of 1,355 metres is quoted in a great many places. No Icelandic authority publishes it in a checkable form.
• The maximum ice thickness. Figures between 250 and 580 metres circulate. The published national inventory does not break out a maximum for this ice cap.
• The year the tunnel was cut. Sources say 2012 and 2015 with equal confidence. The operator's own site gives no date, so neither is stated here.

Everything above the line has a named source beside it. On a subject where a wrong number is copied onward for a decade, that is worth a shorter page.

The figures in one table

Sources

• Náttúrufræðistofnun Íslands — Glaciers
• University of Iceland — Significant glacial retreat since 1890
• Into the Glacier — frequently asked questions

Verify anything time-sensitive before you travel. A Langjokull glacier tour is the shortest way to see most of what is described above, and what each one covers is set out on Langjokull Tours.