Temperature fluctuations inside and outside the cave

The temperature inside the cave is mostly regulated by air exchange through the opening of the cave, as cold air sinks in during the wintertime and cools it down, and then during the summer time the cave heats up due to warmer temperature outside.
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Hallmundur and Hallmundarhraun

The Cave Víðgelmir is located in a lava field called Hallmundarhraun, which is the largest lava field in Borgarfjörður. The field covers about 200 (or 242) square kilometres with an estimated volume of at least two to three cubic kilometers. The total length is about 50-55 kilometers while the field is about 7 kilometers wide at the widest point.
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