"The Great Well! Source of all life on our planet, birthground of our serpent steeds, and the place where you will be judged by our Supreme Master!"
Varn to Luke Skywalker[src]

The Great Well was a large sinkhole on the planet Ophideraan, and home to both the native flying serpents and the Serpent Masters who rode them. The upper levels of the Great Well were given over to Serpent Master dwellings and chambers, while the lowest level, known as the Slave level, comprised an island on which slaves drilled to keep water flowing in the caverns. The sinkhole was linked to a cavern known as the homeland of the serpents.