Háalda is a small part of a vast flood plain where glacial floods from Öræfajökull used to run. It was declared a protected natural monument in 1975, and stands in witness to these great glacial floods.
The depression at Háalda is one of two kettle holes that were formed when two large icebergs ran aground tightly together in the sand dune. When icebergs lay on the surface of the flood plain they would melt in a matter of months, while icebergs that were buried in the sand could take decades to melt, leaving depressions of this kind. These are most commonly referred to as kettle holes, but the locals also have their own terms for them, which translate to "pits" and "iceberg dents”.