Ohma-D'un, also known as the Water Moon, was the largest moon of Naboo. In 32 BBY, following their newfound alliance with the Human people of Naboo, the Gungans established a settlement on Ohma-D'un, bringing multiple specimens of vegetal and animal life to populate the otherwise uninhabited moon. Ten years later, in the early days of the Clone Wars, the Confederacy of Independent Systems used a gas weapon on the moon, killing many of the Gungan colonists in the process.
Ohma-D'un was settled by Gungans shortly after the Invasion of Naboo. Boss Rugor Nass sent Obi-Wan Kenobi, Queen Amidala, Jar Jar Binks, and R2-D2 to the moon prior to the arrival of the Gungans. Obi-Wan and Amidala were to set up a stable ecosystem that could support a Gungan city, aided by Kharl Vanneb, Sakme Kelene, Professor Hallem Celaar, as well as several former members of the Naboo Underground, including Toba. Amidala and Obi-Wan went to the moon in a Mantaris-class amphibious medium transport and were given a sacred animal called the Kresch, which acted as a field guide to wildlife. The Gungans packed the transport with many different types of Naboo animals and plants to populate the moon, such as Saw-toothed granks, tusk cats, shaaks, and kaadu. Humans also established spice mines on the moon.
It was where the defense of Naboo was fought during the Clone Wars in 22 BBY, resulting in the entire Gungan colony almost being wiped out by a poison gas developed by Jenna Zan Arbor.
Victor Flight of the Naboo Royal Space Fighter Corps often made runs out to the moon.