Lóndrangar are a pair of volcanic plugs left out as remnants from a bigger crater, which has since mostly eroded away with time. It is reckoned though, that the rock in the slopes of nearby Svalþúfa is an isolated part of the original rim around the crater itself, with the rest eroded away by the sea. There is some considerable nesting of birds in the steep slopes of the twin cliffs and various kind of birds can be observed in Lóndrangar, the majority of which are Black-legged Kittiwake, Langvía, lundar and fýlar. Awhile back[when?] the coastal area around Lóndrangar, Drangsvogur, would be used for the landing of fishing vessels with 12 fishing boats making use of it as a natural harbor in its heyday.