Tysfjord (Norwegian) or Divtasvuodna (Lule Sami) is a municipality in Nordland county, Norway. It is part of the Ofoten traditional region. The administrative centre of the municipality is the village of Kjøpsvik. Tysfjord was separated from the municipality of Lødingen in 1869.
Tysfjord is the only municipality in Norway where speakers of Lule Sami should theoretically be able to speak that language with officials (since it is one of the official languages of the municipality), although this has not come to fruition. The Árran Lule Sami Center is located in the Tysfjord village of Drag.
The municipality is named after Tysfjorden. Tysfjord is a Norwegianized form of the Sami name Divtasvuodna (first recorded around 1520 as "Tyttisfiorden"). The meaning of the first element divtas is unknown. (A popular belief, and common interpretation, is that the first element should be the genitive case of the name of the Norse god Týr - but this does not fit either with the Sami form or the oldest spellings of the name.) The last element is vuodna which means "fjord".