Heimaey is most famous for the nearly six-month-long volcanic eruption in 1973 that added some 2.2 square kilometers (0.9 square miles) to the island’s total area. This part of the eastern coast of the island will be pointed out to you if you embark on one of the popular circumnavigations of Heimaey. Other sights along the way include the cliffs near the harbor, home to a number of bird colonies—an estimated six to eight million birds are said to live on the island, including gannets, guillemots and puffins. The Klettshellir cave is large enough for boats to enter, and occasional concerts here show off its surprising acoustics. Finally, while whale sightings can't be guaranteed, there is a significant population of orcas in the summer, as well as other species in smaller numbers year-round, so your odds are pretty good.