Volan III was the inhabited third planet orbiting the primary Volan, in the Alpha Quadrant. This system was located on the Cardassian side of the Demilitarized Zone, and was one of the Federation's Volan colonies. The world had at least one moon.
Lieutenant Commander Calvin Hudson, Starfleet's attaché to the Federation colonies in the DMZ, was stationed on Volan III in 2370. There, he and various leaders from the other colonies met to discuss relevant matters, including the formation of the Maquis. That year, Gul Dukat took Commander Benjamin Sisko to Volan III to convince him that there were Federation colonists willing to commit acts of violence against the Cardassians, such as the destruction of the Bok'Nor. Upon their arrival, Gul Evek confronted the colony leaders with the information obtained from William Samuels, and accused them of participating in an official Starfleet plot to secretly arm the colonists against the Cardassians – while at the same time the Cardassian Central Command was arming its own citizens in turn. (DS9: "The Maquis, Part I") Sisko visited Volan III a second time, to issue a warning to the Maquis, that by making the Cardassians their enemy, the were making the Federation their enemy as well. (DS9: "The Maquis, Part II")
Raymond Boone, or rather a Cardassian operative surgically altered to resemble him, settled with his family on Volan III to operate a ladarium mining sluice following his return from Cardassian custody after Setlik III. (DS9: "Tribunal")
The matte for Volan III was a reuse of a matte created for Tau Cygna V in Star Trek: The Next Generation episode "The Ensigns of Command". As such, the tube-like structure running up the mountain might be identified as an aqueduct.
According to Star Trek: Star Charts (p. 47) and the Stellar Cartography: The Starfleet Reference Library ("Federation Historical Highlights, 2161-2385"), Volan III was located in the Volan system.