Ukonkivi, (English: Ukko's rock), is located on the island of Ukonsaari in lake Inari, Finnish Lapland. The Inari Sami name for the island is Äijih. The area of the lake is called Ukonselkä. Ukonkivi was considered by the local Inari Sami to be an extremely important siedi (Inari Sami: siejdi, Finnish: seita) or sacred natural formation and was used as a sacrificial site, perhaps as recently as in the 19th century. The names "Ukko" and "Äijih" refer to sky deities in the Finnish and Sami mythologies, respectively.

The island is about 30 metres high, 50 metres broad and a 100 metres long. The distance from the village of Inari to Ukonkivi is approximately 11 kilometres. There are guided tours to the site during the summer from the harbour of the Sami museum Siida.

There are two known siedis at Ukonsaari. The first one to be studied was a sacrificial cave. One of the most important archaeological findings in Lapland[citation needed] was made at Ukonkivi in 1873 by the British archaeologist Sir Arthur Evans, when a silver jewelry fragment was found in the cave. An additional siedi was discovered in 2007 by Finnish archeologists.

The names of some of the numerous islands adjacent to Ukonsaari may suggest other religious sites, for example:

Palo Ukko (Finnish: Fire-Ukko)

Pikku Ukko (Little Ukko)

Ukonkarit (Ukko's skerries, a series of islets close to Ukonsaari)

Hautuumaasaari (Burial ground island)

Aviosaaret (Marriage islands)

Tissikivisaari (Breast-stone island)

Junttisaari (Lad island. Juntti is a complex word approximately meaning a juvenile yet adolescent male.[citation needed])

Vanha hautuumaasaari (Old burial ground island)

Ristisalmensaaret (Cross sound islands)