malformalady:

The Dead Zone in the Gulf of Mexico is a large region of water that has very low oxygen concentrations, and therefore can’t support aquatic life. Dead zones can be found worldwide. The Gulf of Mexico dead zone is one of the largest in the world. Marine dead zones can be found in the Baltic Sea, Black Sea, off the coast of Oregon, and in the Chesapeake Bay. Dead zones may also be found in lakes, such as Lake Erie.