Tanuga IV was the fourth planet in the Tanuga planetary system. The atmosphere was capable of supporting humanoid lifeforms. This was the homeworld for the Tanugans, a highly advanced humanoid species.
A lambda field generator, one integral part of Doctor Nel Apgar's work on Krieger waves (the other being the Krieger wave converter, located on the Tanuga IV research station in orbit of the planet) was located on Tanuga IV. Shortly before the destruction of the station, Manua Apgar and Tayna beamed down to the planet, saving them from certain death. The Tanugan security force, represented by Chief Investigator Krag, was operating from the planet. (TNG: "A Matter of Perspective")