Between Kirkjubæjarklaustur and Landmannalaugar, the eruptive fissure Eldgjá is to be found. Eldgjá is a 40 km long eruptive fissure, 600 meters wide in many places, and up to 200 meters deep, formed in a gigantic eruption in 934. From Eldgjá, extensive streams of lava have flowed through Landbrot and Meðalland, reaching sea at Alviðruhamrar in Álftaver. The lava-field is believed to cover 700 km², which makes it one of the vastest lava-fields on earth since the last ice age. Eldgjá is believed to belong to the same crater system as Katla. Eldgjá is a unique natural phenomenon and is listed as natural remnants.
Eldgjá is a part of a volcanic fissure that stretches from Mýrdalsjökull almost to Vatnajökull. Eldgjá is about 8 km long, 600 m wide and up to 150 m deep. It was formed in the year 939 during one of the largest volcanic eruptions in Iceland in historical times. Eldgjá‘s main attraction is the waterfall Ófærufoss, located a short walking distance from the area‘s car park.