Lake Seydozero (Russian: Сейдозеро, romanized: Seydozero, Kildin Sami: Сейдъявврь, romanized: Sejdjavvr') is located on the Kola Peninsula, in Murmansk Oblast within the Lake Lovozero and ensures runoff to the river Seydyavryok. "Seyd" translated from the Sami language means "sacred".

The lake is located at an altitude of 189 m above sea level. The length of the Seydozero is 8 km, the width is from 1.5 to 2.5 km.