The Reykjanes peninsula was formed from volcanic activity and along the coast, low cliffs alternate with sandy beaches where the open ocean washes up unobstructed. The vegetation there is sparse and simple. Low fronts often travel further inland from the southwest causing variable weather and considerable precipitation. Quite a large colony of arctic terns can be found out by the lighthouse on Reykjanes peninsual and the largest gannet colony on the Icelandic coast is on Eldey island. Gannets may often be observed on Karlinn, a lone tor just off the coast. Farther to the west along the coast is Hafnaberg where all auk species that nest in Iceland may be seen, with the exception of the little auk. There are plenty of kittiwakes on the rock in addition to sea ravens and other birds. At Hafnir, one can observe the great northern diver and the harlequin duck in winter and many other species year round. Rich birdlife can be observed on ponds and shores near Sandgerði. Garðskagi, which is on the outermost tip of the Reykjanes peninsula, is an important stopover for nordic nesting species, such as the redbreast, the turnstone and the sanderling. Stray birds can also be seen there in the migration periods.