Surtshellir

[3][4] Surtshellir was formed as a lava tube in a massive, effusive, shield-volcano eruption at the northern end of the Prestahnúkur volcanic system.

At least three and possibly four vents opened on the edge of Langjökull glacier during this long-lived eruption, which has been dated to the first decades of Iceland's settlement (c.

[13][12] However, the earliest reference to the cave by name, in the 12th-13th century Icelandic "Book of Settlements" (Landnámabók) describes the 150 km journey of a chieftain's son, Þorvaldur holbarki ("hollow throat") Þorðarson, through Iceland's interior to sing a poem of praise (a "drápa") – a ritual act – to the giant that lived inside "hellisins Surts", Surt's cave.

Both caves were profusely decorated with lavacicles and lava stalagmites in the past, based on survey of the broken stubs and shattered pieces of these formations.

[17] This has resulted from both deliberate vandalism from souvenir hunters and from high traffic through the caves with visitors bumping into and breaking the fragile formations.

One of four entrances to the Surtshellir lava tube in the Hallmundarhraun lava field.
Looking up towards the fourth (lowest and farthest west) entrance to Surtshellir, seen from within the section of the cave called Íshellir (ice-cave). The white slab is ice, which was preserved into summertime.
Typical passage shapes in the Surtshellir-Stefanshellir lava tube system, showing intact walls and pahoehoe floors