The Trondheimsfjord (or Trondheimsfjorden), an inlet of the Norwegian Sea, is Norway's third longest fjord at 130 kilometres (81 mi) long. It is located in the west central part of the country, and it stretches from Ørland in west to Steinkjer in north, passing the city of Trondheim on its way. Its maximum depth is 617 metres (2,024 ft), just inside of Agdenes.
The largest islands in the fjord are Ytterøy and Tautra; the small Munkholmen is located near the harbor of Trondheim; and there are several islands at the entrance of the fjord. The narrow Skarnsundet is crossed by the Skarnsund Bridge. The part of the fjord to the north of the strait is referred to as Beitstadfjorden. The main part of Trondheimsfjord is ice free all year; only Verrasundet, a long and narrow fjord branch in the northern part of the fjord, might be ice covered in winter. The Beitstadfjorden might also freeze over in winter, but only for a few weeks.
The towns Stjørdal, Levanger, and Steinkjer are found on the eastern and northeastern shore of the fjord. Aker Verdal in Verdal produces large offshore installations for the petroleum sector. A yard in Rissa completed the luxurious apartment ship MS The World. Fiborgtangen is a peninsula along the eastern shore of the fjord where a large paper mill owned by Norske Skog is situated.
Trondheimsfjorden has a rich marine life, with both southern and northern species; at least 90 species of fish have been observed, and the fjord has the largest biological production among Norway's fjords.[1] In recent years deep water corals (Lophelia pertusa) were discovered in the fjord, not far from the city of Trondheim. Several of the best salmon rivers in Norway empty into Trondheimsfjord. Among these are Gaula (in Melhus just south of Trondheim), Orklaelva (in Orkdal), Stjørdalselva (in Stjørdal), and Verdalselva (in Verdal).
The lowland east and south of the fjord represents one of Norway's best agricultural areas. The more rugged and mountainous Fosen peninsula is situated to the west and northwest, giving some shelter from the wind common to coastal areas.
The Trondheimsfjord was an important waterway in the Viking Age, as it is still today. In 1888, an undersea mudslide caused a tsunami which killed one person in Trondheim and ruptured three railway lines.
Four giant squids have been found in the fjord, which is among the highest concentrations in the world.[2]
The fjord is named after Trondheim - but originally the name of the fjord might have been just *Þrónd or *Þróund in Old Norse. A name like that would be related to the verb þróast which means to "thrive" or "flourish" and the name Þrór which means "likeable" or "stoutish" (and it was one of Odin's nicknames).
If this is the case, then the people living around the fjord (the þrœndir, see Trøndelag) named themselves after the fjord. (Compare sygnir which means "the people living around the fjord Sogn".)