The Lost Seas
Sea of Silt
The Sea of Silt is a massive body of silt that forms the eastern border of the world of Athas; somewhere within it far to the east is Ur Draxa, the city of the Dragon. Unlike water, the silt in the Sea of Silt cannot be swum in or floated on; anything that settles on the silt immediately sinks to the bottom. This makes it one of the deadliest and most perilous places on Athas.
There are two primary methods for traversing the silt. 99% of travel is accomplished by using silt skimmers which roll on giant wheels. Because nothing floats on silt, these ships can only travel in areas of the Silt Sea that are no deeper than the wheels are tall. This means that virtually all the traffic and trade in the Sea occurs in the shallows by the shore (which usually stretch out much further than the shallows in oceans in other worlds); to cross the deeper parts of the Sea, sailors need to use complex maps or their own knowledge to travel on “ridges” (basically, the tops of undersilt mountain ranges) that run through some of the deeper, otherwise uncrossable parts of the Sea. Giants, who travel the Silt Sea by wading chest-deep, often know these ridges and pathways well.
The second method of travel in the silt is much rarer: psionic or magic powers that allow travellers to fly above the silt or skim across the surface without sinking. The sorcerer-king of Balic, Dictator Andropinis, maintains a powerful and expensive fleet of psionicist-piloted dromonds that resemble real-world sailing ships. Levitating on the surface of the silt, they can move swiftly and freely in the Sea, anywhere they choose. Only these powerful psionic ships are able to travel far eastward where the Sea deepens and no pathways are known.
There are many shardmind communities scattered in the Sea; because shardminds do not need to eat or breathe, they are perfectly comfortable stationed on an isolated, unreachable rock. There are many shardmind silt sailors (if they fall overboard, unlike every other race, they sink but don’t instantly die, but instead have to slowly trudge back to land along the bottom of the Sea and hope to avoid being attacked by one of the many monsters living in the silt) and, due to their psionic power, many shardminds in the employ of Balic (which uses psionicists to float its navy across the silt).