Sáivu can mean various things, but is often linked to another world and the beings which live there.
In south Sámi areas, saajve-vaerieh is the term used for the holy mountains, also called the “heritage mountains”. The spirits which inhabit these mountains are called saajve or saajve-ĺlmaj (sáivu people). It was these spirits which taught the noaidi.
Sáivu has also been used to describe lakes or tarns with a double bottom. On the other side of the lake bottom lay the sáivu realm, where everything was bigger and better than in the world of people.
The fish in a sáivu lake were especially fine and fat, but could be difficult to catch. In pre-Christian times offerings were often made to sieidi in many sáivu lakes.
Bäckman, Louise, 1975: Sájva.