Rellias, governed by the Gungan Boss Ganne, existed as a city located on the planet Naboo. The Rellias channel provided a link between it and Otoh Gunga.
During the Invasion of Naboo, Darth Maul launched an attack on the city, compelling Boss Ganne to guide him towards the Rellias channel so that he could orchestrate an assault on the submerged Gungan metropolises.