Tjörnin
Feeding the birds on the lake shores is a popular pastime, so much that it has been referred to as "the biggest bread soup in the world".
Geography
Tjörnin is described as a lagoon next to a barrier beach. The lake's formation is attributed to the lagoon which was part of a reef that existed at the present location of Hafnarstræti (a city street, "Harbour Street"). This street, which passes through the business section of the city, lies on the southern side of the lake and leads to the gardens. The Vatnsmýri marsh feeds the lake. The outflow from the lake is Lækurinn, previously an open water channel flowing through the city centre, but since 1911 part of the sewage system under Lækjargata. During the winter, the lake usually freezes periodically and is used for ice skating. The average depth is 0.57m (1.9 feet) with the deepest point at 0.8m (2.4 feet). Both banks of the lake are paved and terminate at the Hljómskálagarður (formally known as Tjarnargarður), a well-tended park decorated with statues to the south of the lake. The winding paths are frequented by joggers and cyclists. Notice boards along the shore give daily reports of the numbers of birds on the lake.
Avifauna
The lake is frequented by between 40 and 50 species of water birds, including the Arctic tern, the Eider, the Gadwall, the Greylag goose and other species of goose, the Mallard, several species of seagulls, and the scaup. Whooper swan are viewable within close proximity. The Arctic tern’s arrival heralds the start of summer. Birders from all over the North Atlantic come to pursue their hobby in the lake area. The lake is also a favorite place to take young children to watch and feed birds. The popularity of bird feeding has led to the lake being poetically referred to as "the biggest bread soup in the world" (stærsta brauðsúpa í heimi). Lately, however, preying seagulls have caused the City Council to issue warnings to residents, asking them to refrain from feeding the ducks in Tjörnin to avoid putting ducklings at risk.