Located west-southwest of Reykjavík, the island of Eldey covers an area of about 3 hectares (7 acres), and rises to a height of 77 metres (253 ft).

[1] Its sheer cliffs are home to large numbers of birds, including one of the largest northern gannet colonies in the world, with around 16,000 pairs.

[5]: 74 The latest confirmed eruption of the Eldey axial volcanic ridge occurred at its northern extremity in 1926 and it may have been active in 1970.

[5]: 77–8  A tephra eruption northwest of Eldey dusted the western shore of the Reykjanes Peninsula of Iceland occurred in June 1879.

[4] The island formerly supported the last remnant population of the flightless great auks, after the birds moved there from Geirfuglasker following a volcanic eruption in 1830.