Tyrifjorden (Lake Tyri) is a lake in
Norway. It lies northwest of Oslo and is the nation's
fifth largest lake with an area of 139 km
2.
It has a volume of 13 km
3, is 295 meters deep at its deepest, and lies 63 meters above sea level. The lake's primary source is the
Begna river, which discharges into Tyrifjorden at
Hønefoss where the river forms the waterfall of Hønefossen. Its primary outlet is at
Vikersund near the lake's southwest corner, where Tyrifjorden discharges into the
Drammenselva river.
Location

Tyrifjorden is located in the county of
Viken and borders the municipalities of
Hole,
Lier,
Modum
Modum is a municipality in Buskerud in Viken county, Norway. The administrative centre of the municipality is the town of Vikersund. The municipality of Modum was established on 1 January 1838 (see formannskapsdistrikt).
The area has a long tr ...
, and
Ringerike. Tyrifjorden is a landlocked
fjord. It consists of a main body, Storfjorden, along with the Holsfjorden, Nordfjorden, and Steinsfjorden branches.
Branches
*Nordfjorden – This is the northernmost fjord arm of Tyrifjorden
*
Steinsfjorden
Steinsfjorden is a branch of the lake Tyrifjorden located in Buskerud, Norway. It has a length of about eight kilometers, stretching from the sound Kroksund at Sundvollen northwards to Åsa, in the municipalities of Ringerike and Hole. At th ...
– This is the northeastern arm of Tyrifjorden
*Holsfjorden – This is the southeastern arm as well as being the longest and largest of the fjord branches
Islands
*
Utøya – camp site for events
*Storøya – with a golf club
*Frognøya
The name
The
Old Norse form of the name was just ''Tyri'' (or ''Tyrvi''). This uncompounded name is also the first element in the name
Tyristrand. The name is derived from the word ''tyri'' meaning "old/dead
pine (wood)", referring specifically to the woods of the western side of the lake. The last element ''-fjorden'' (the finite form of
fjord) is a later addition.
2011 shooting massacre
On 22 July 2011, an island in the lake,
Utøya, was the site of a shooting spree during a youth camp held by the
Norwegian Labour Party
The Labour Party ( nb, Arbeiderpartiet; nn, Arbeidarpartiet; A/Ap; se, Bargiidbellodat), formerly The Norwegian Labour Party ( no, Det norske Arbeiderparti, DNA), is a social-democratic political party in Norway. It is positioned on the centr ...
.
References
External links
Moonlight at TyrifjordenFrost Mist Over Lake Tyrifjorden
Lakes of Viken (county)
Lier, Norway
Ramsar sites in Norway
{{Viken-geo-stub