Which rank corresponds to O6 in the naval hierarchy?

The rank that corresponds to O6 in the naval hierarchy is Captain. In the United States Navy, the officer ranks are categorized by an alphanumeric code, known as a pay grade system, where the letter 'O' stands for officer and the number represents the rank level. O6 indicates a senior officer rank, and in the Navy, this is specifically designated as Captain.

To provide further context, a Commander, which is O5, is ranked just below a Captain and is typically responsible for smaller ships, aviation squadrons, or major shore installations. Meanwhile, a Rear Admiral Upper Half, which corresponds to O7, is a flag officer rank above Captain, and a Vice Admiral, at O9, is further up in the hierarchy. Understanding these distinctions is essential for grasping the structure of naval command and the responsibilities associated with each rank.