Jökulsárgljúfur is about 25 km long canyon of the glacier river Jökulsá á Fjöllum. The canyon is up to 120 meters deep and about 500 meters wide. Jökulsárgljúfur extends from Selfoss waterfall in the south and north to Ásbyrgi. It was formed in a catastrophic glacial outburst floods due to melting of glaciers that occurred at the end of the last Ice Age, about 10 thousand years ago. Volcanic activity has also shaped the Jökulsárgjúfur canyon, and there are many interesting geological formations that have formed from the interaction of water and lava, including basalt columns, pillars and cliffs.
Jökulsárgljúfur is a protected area in North Iceland and in 2008 it became a part of Vatnajökull National Park. The canyon is a paradise for hikers, there are many interesting hiking trails which are undoubtedly the best way to enjoy this natural phenomenon. During the summer it is possible to camp in Ásbyrgi and in Vesturdalur valley, both very good camping sites.
In the year 2014, Bárðarbunga a big central volcano woke up, causing a great deal of concern because of the possibility of an volcanic eruption underneath the Vatnajökull glacier. That would have led to a great melting of ice, which would have caused a glacier outburst flood in the river Jökulsá á Fjöllum and down the Jökulsárgjúfur canyon. Fortunately, the eruption broke up north of the glacier on the black sand plain between Herðubreið mountain and Dyngjujökull glacier, with lava flowing and eventually covering about 85 km2. Bárðarbunga volcano is still alive, so it's impossible to say what happens there in the next couple of years.
It is possible to see the canyon from many locations. It can be seen from Dettifoss waterfall and from Hafragilsfoss waterfall, located close to Dettifoss. From Ring Road nr. 1 take road nr. 864 for about 25 km, first you will see the turn for Dettifoss and the next one is for Hafragilsfoss. It is also possible to experience the canyon from the campsite in Vesturdalur valley.