What is the highest rank indicated by O-11 in the Navy?

The rank indicated by O-11 in the Navy is Fleet Admiral. This is the highest possible rank that can be achieved in the Navy, ranking above Admiral, which is an O-10. The position of Fleet Admiral is a five-star admiral rank that has been conferred only in certain circumstances, typically during major conflicts, such as World War II. It is a rank that signifies a position of great responsibility and leadership over significant naval forces. Fleet Admirals have authority over large fleets and are expected to demonstrate exceptional strategic competence. This rank has not been appointed since World War II, but it remains an important part of naval history and structure.