it was an important transport route. Today, aside from minor leisure boating and the steamship Skibladner, there is no water traffic on the lake. Most of its shores are dominated by rolling agricultural areas, among them some of the most fertile grainlands in Norway. The main train line, the Dovre Line between Oslo and Trondheim, goes along its eastern shore, making stops at Hamar Station and Lillehammer Station. From the south, the European route E6 highway runs along the eastern shore of the lake until the Mjøsa Bridge connects Moelv on the east with Biri on the west. Mjøskastellet The largest and only island in the lake is Helgøya. Except for Helgøya, Mjøsa only contains small islets. The most interesting of these is Steinsholmen, which holds the ruins of Mjøskastellet, a medieval citadel dating from the 13th century. Established by King Haakon IV of Norway, it was first mentioned historically in a letter dated 1234. Peter Andreas Blix documented the site and made drawings in 1897. Hedmark Museum has a future archaeological plan for the site. Fish Lake Mjøsa has 20 species of fish. Among the most common are pike, European perch, common roach, greyling, and the hundertrout, a brown trout which can reach a weight more than . Another common species is the European smelt, which is the most important bait fish for the predators. Historically, the most economically significant species is the lågsild (European cisco). Source of drinking water Several municipal and urban areas use the lake as their source of drinking water. Hamar / Ottestad – Hias IKS has responsibility for the waterworks and waste water treatment plants in Hamar Municipality, Stange Municipality, and Løten Municipality. Lillehammer – Operates waterworks at Korgen. Contracts have been signed for a new flood-proof waterworks to be built in Hovemoen. Gjøvik – WWTP run from Rambekk Renseanlegg Østre Toten – Kapp / Skreia Brumunddal – Biri / Moelv Name The lake is named "Mjøsa" ( / Proto-Norse *Merso) and this name must be very old. The meaning is possibly "the bright/shiny one". This is based on the theory that the first element *mer- is related to the English word mere which means "clear" or "bright" and -so is a suffix. Events From 1932 to 1934, ice racing was held on the lake's northern reaches near Lillehammer. Warmer winters had forced race organisers to move racing from Gjersjøen near Oslo. The Norwegian