Syðradalur has six inhabitants and covers 16 merkur and 12 gyllin, of which 6 merkur and 4 gyllin are copyhold land, which is leased by a single copyhold tenant, and 10 merkur and 8 gyllin are freehold land. The sheep herd consists of 420 animals.

The old village of Blankaskáli, first mentioned in 1584, was hit by an avalanche in 1809. No one died, but the traces of the repeated and deadly avalanches in Gerðum on Borðoy frightened the inhabitants, so they moved to the eastern part of the island where the village of Syðradalur was founded in 1812. The last inhabitants left Blankaskáli in 1816, which has since been deserted.