Hazrat Usman made 1st Islamic navy on which sea:

The correct answer is Mediterranean Sea. Hazrat Usman RA (the third Caliph) established the first Islamic navy on the Mediterranean Sea in the year 649 CE (29 AH). The navy was created to defend the Muslim territories from Byzantine attacks from the sea. Muawiyah RA, the governor of Syria, played a key role in establishing this navy. The Red Sea and Black Sea are also near the Islamic world, and the Dead Sea is a saltwater lake, but the first Islamic naval fleet was on the Mediterranean Sea. Therefore, Mediterranean Sea is the correct answer.