In Norse mythology

Norse mythology

Norse mythology, a subset of Germanic mythology, is the overall term for the myths, legends and beliefs about supernatural beings of Norse pagans. It flourished prior to the Christianization of Scandinavia, during the Early Middle Ages, and passed into Nordic folklore, with some aspects surviving...

, Nidavellir (Dark fields) is one of the Nine Worlds and home of the Dwarves. Hreidmar

Hreidmar

In Norse mythology, Hreiðmarr is the avaricious king of the Dwarves, who captured three gods with his unbreakable chains. He was father of Fafnir, Ótr and Regin. He owned a house of glittering gold and flashing gems built by Regin and guarded by Fafnir. After Otr was accidentally killed by Loki,...

 is the king of Nidavellir.

Völuspá

It is mentioned in the Völuspá

Völuspá

Völuspá is the first and best known poem of the Poetic Edda. It tells the story of the creation of the world and its coming end related by a völva addressing Odin...

:

Stóð fyr norðan, / á Niðavöllom / salr úr gulli / Sindra ættar

("North, on the Niðavellir, stands the dwelling place of Sindri's kin, Covered with gold").

Sindri was a famous dwarf. It might be related to the later-mentioned Niðafjöll (the Dark Fells), a mountain chain in the underworld. Niðavellir has often been interpreted as one of the nine worlds of Norse cosmology

Norse cosmology

The cosmology of Norse mythology has 'nine homeworlds', unified by the world tree Yggdrasill. Mapping the nine worlds escapes precision because the Poetic Edda often alludes vaguely, and the Prose Edda may be influenced by medieval Christian cosmology...

. As such it might be identical to the Svartálfheim mentioned in the Prose Edda

Prose Edda

The Prose Edda, also known as the Younger Edda, Snorri's Edda or simply Edda, is an Icelandic collection of four sections interspersed with excerpts from earlier skaldic and Eddic poetry containing tales from Nordic mythology...

by Snorri Sturluson

Snorri Sturluson

Snorri Sturluson was an Icelandic historian, poet, and politician. He was twice elected lawspeaker at the Icelandic parliament, the Althing...

; as svartálfar

Svartálfar

In Norse mythology, svartálfar are beings who dwell in Svartálfaheimr . Both the svartálfar and Svartálfaheimr are solely attested in the Prose Edda, written in the 13th century by Snorri Sturluson...

(black-elves) are generally thought by scholars to be a synonym used only by Snorri for dvergar (dwarves).