The Great Trash Patch

Out in the far flung Pacific there is the Great Trash Patch. A huge mass of waste and debris deposited by the currents that has slowly accumulated for decades upon decades. The Patch consists mostly of items washed off or toss over the side of ships and massive amounts of commercial fishing nets. The Patch also contains materials that have been swept out to sea after a disaster. 
The debris is several meters thick, drifting on the surface with bits dangling below entangled in nets. In parts the waste is so entwined that it has created islands that are dry. Though mainly it is a soup that can be barely swam through. The entire region is home to scavengers that feed on tho carcasses of unfortunate creatures that have drowned and suffocated in the morass.
There are other scavengers, the metahuman kind out in the Patch as well. These people live by securing shipping containers and retrieving what wealth might be found inside. They have been known to lash whatever floats together and create barge towns that they move to and fro with small boats. There is a strong criminal element in these barge towns as well. Pirates, smugglers and people trying to hide.
A small commune of freedom no law anarchists calling themselves Oceania have been building a truly habitable floating island. By acquiring through donations freely given or not they have had several thousands of tons of volcanic pumice which has a lower density than water shellacked and then pressed together to form huges sheets that they have then used to build their island. They have been able to gather enough other soils and add biomass that they find floating to be able to have small orchards of palms and other low ground crops to eat along with whatever seafood they can obtain.