Imagine a world inhabited by dragons of such a tremendous size, that everything else actually lives INSIDE them (because it is too dangerous to live OUTSIDE of such big dragons - they will stomp and burn you like a microbe).
So, their blood vessels are rivers, and various organs are different countries. There is an elemental realm of Air - their lungs; elemental realm of Fire - fire-producing organ; psionic realm inside their brains; divine realm around their hearts; intestines are kind of a dark marsh; and there is the lower hell of the rectum, where demons damp the souls of sinners (and sinners still alive) to be mercilessly excreted outside...
And if you want to travel from dragon to dragon, you`ll have to wait for the right opportunity - I think I don`t need to explain...
So, their blood vessels are rivers, and various organs are different countries. There is an elemental realm of Air - their lungs; elemental realm of Fire - fire-producing organ; psionic realm inside their brains; divine realm around their hearts; intestines are kind of a dark marsh; and there is the lower hell of the rectum, where demons damp the souls of sinners (and sinners still alive) to be mercilessly excreted outside...
And if you want to travel from dragon to dragon, you`ll have to wait for the right opportunity - I think I don`t need to explain...