This strait, vital to world commerce, twists around the end of the Mazandaram Peninsula--the end of Arabia, and connects the Persian Gulf to the Gulf of Oman. It is 100 nautical miles long, 48 to 80 kilometers wide and 55 to 91 meters deep. It separates Oman from Iran. Near the Iranian coast is the large island of Qeshm. It is part of the Indian Ocean.