Víðgelmir, one of the biggest lava-caves in Iceland, ca. 1 km southeast of Fljótstunga, the uppermost farm in the Hvítársíða district. Many stalagmites and stalacites, some evidence of ancient dwellings there.

The cave has been preserved since 1993 and entrance is only allowed with guidance. Guides from Fljótstunga arrange short (1 hour) and long (3-4 hours) tours.