The landscape of the Transitive Isles is dotted with caverns, tunnels, and underground ruins. Rumors persist however that there may be more then just isolated caverns beneath the ever shifting earth and sea.
Very little concrete information exists regarding the depthworld. Most residents relegate it to the stuff of childrens tales and nightmares. Experts residing on the various isles maintain that there is a huge network of interconnected caves that run beneath the shifting seas, connecting to the isles in ways both mundane and magical. Some even theorize that Daunton has remained at the focal point of the transitive isles for so long because of a physical connection to the depthworld that holds it in place. However the only thing that can be said for certain is that The Depthworld, if it exists, is a place of danger and strange alien sights unlike the surface world.
Tales of The Depthworld have a strong following in The Valley of Bone. The locals talk of Xibalba as if it extends for miles, and battered adventurers have been known to stumble back to civilization raving about portals, and beasts lurking in the shadows. While sages theorize that Xibalba and The Depthworld may be one and the same, it is difficult to say with so little evidence.