The other world as the part of mythology
Despite the differences in the ideas on the location of the other world, it was always the part of the general mythological picture of the world. It was always described as the world opposite to the real world of live people. And its location in horizontal space was always correlated with the vertical model of the world that divided the world into the sky, earth and hell.
In such way the tribes of Siberia put their other world near the Siberian rivers and in the lowest world. In some countries of Oceania and Northern Africa the other world was situated somewhere in the West as these tribes had the cult of the sun. Therefore the light came from the East as the sun rises in the East.
Rarely the other world was put to the sky among stars where people could get as to the lowest world with the help of the world tree or the bridge. This bridge was usually either the rainbow or the Via Lacteal.
Sometimes it had the certain location to which people travelled to see their dead relatives. And myths were full of such visits to the netherworld. For example the Greece myths tell us about the Hercules that travelled to the other world and the Orpheus who managed to get into the netherworld without dieing.
In general it was considered to be very complicated to get to the other world as it was always guarded by some creature. And even if you manage to come through the guarder a great number of difficulties are waiting for you later. Besides the other world was also divided into several parts to which the dead people got in dependence on the people's deeds during their life.