Manu III was the third planet in the Manu planetary system. It was an inhabited planet.
The planet was once visited by Worf, where he saw proximity detectors in use, which helped him to recognize them on Turkana IV. (TNG: "Legacy")
Manu III appeared in the starchart Data and Picard were studying in Stellar Cartography in 2371. (Star Trek Generations, display graphic)