The campaign of Tartessos is focused on the environment of the city itself, its environs, and its culture and beliefs. The cosmology of the world Tartessos is therefore simplified and reflects the belief systems of the people living the city, while still leaving plenty of room for strange creatures.
The scholars of Tartessos divide the cosmos into three Worlds: the Heavens, the Middle World, and the Underworld. The Middle World is also divided into three worlds: the Earth, the Water and the Air. Generally in modern times these are simply described as five distinct planes of existence, and the notion of a Middle World is falling into disuse.