Stepan Osipovich Makarov was a Russian vice-admiral, commander in the Imperial Russian Navy, oceanographer, member of the Russian Academy of Sciences, and author of several books. He was a pioneer of insubmersibility theory, and developer of a Cyrillic-based semaphore alphabet. A proponent of icebreaker use, he supervised the first ever polar icebreaker construction. Makarov also designed several ships.