[4] Due to the mountain's steep and unstable sides, the first definite ascent was in 1908 by Hans Reck and Sigurður Sumarliðason, despite centuries of knowledge of its existence.

In former times, outcasts who had been excluded from Icelandic society because of crimes they had committed lived in the Ódáðahraun and accessed the oasis.

[1][11] It is separate from the present potentially active fissure swarms and central volcanoes nearby and is believed to be inactive.

[10]: 8  If as happened in Herðubreið's case the eruption in its last stage became again sub-aerial with a lava cap and a spatter cone or crater vent.

[4] While by the end of glaciation, Herðubreiðar was extinct, volcanic activity resumed for a time at Herdubreidartögl to its south with fallout deposits and olivine tholeiitic lava flows in a much more spread out fashion.