The Divine Realms are the home of the gods and many immortals. They exist on a different plane or dimension from the Mortal Realms and can only be reached by mortals through the help of gods or immortals. That's how Veralidaine Sarrasri and Numair Salmalín passed through the realms. When they got into the Divine Realms they were pulled into them by Daine's parents. For returning to the Mortal Realms they had to ask the dragons for their help.
The Divine Realms are the major setting in The Realms of the Gods.