The affairs of Eberron’s surface dwellers are well known and well documented, but very little is known or recorded about the intelligent life that thrives beneath Eberron’s seas. Anyone who’s travelled by sea from Khorvaire to Xen’drik has likely dealt with the Sahuagin, but very few know about the vast underwater society of which they are but a small part. Beneath Eberron’s seas lie vast civilizations as complex and filled with as much intrigue as the cities of the surface world the largest and most cosmopolitan of which is Madidus.
Madidus is the undersea equivalent of Sharn. All intelligent aquatic races live, play and do business here. It’s the centre of underwater commerce. Much like Sharn, Madidus was built around a manifest zone. Where Sharn’s connection to the plane of Syrania allows building to reach heights that seem impossible, Madidus is connected to the plane of air which crates permanent pockets of breathable air. This allows surface dwellers to live in Madidus comfortably. The area of the city enveloped with breathable air is home to hundreds of people from the surface including Humans, Elves, Dwarves and Halflings. Few who end up here make any effort to leave.