Strait of Hormuz

The Strait of Hormuz ( Persian: تنگهٔ هُرمُز Tangeh-ye Hormoz , Arabic: مَضيق هُرمُز Maḍīq Hurmuz) is a strait between the Persian Gulf and the Gulf of Oman. It provides the only sea passage from the Persian Gulf to the open ocean and is one of the world's most strategically important choke points. It has been so for centuries, with vast hinterlands rich in luxury trade goods, but no easy access to lucrative trading ports. Babur's memoirs recount how almonds had to be carried from the distant Ferghana region in Central Asia to Hormuz to reach markets.

On the north coast lies Iran, and on the south coast lies the Musandam Peninsula, shared by the United Arab Emirates and the Musandam Governorate, an exclave of Oman. The strait is about 104 miles (90 nmi; 167 km) long, with a width varying from about 60 mi (52 nmi; 97 km) to 24 mi (21 nmi; 39 km).

During 2023–2025, 20% of the world's liquefied natural gas and 25% of seaborne oil trade passes through the strait annually. As of June 2025, the strait has never been closed during Middle East conflicts, unlike the Straits of Tiran, though Iran threatens to close the strait, and preparations to mine it have been undertaken.

Etymology

Popular etymology derives "Hormuz" from the Middle Persian pronunciation of the name of the Zoroastrian god Ahura Mazda. Alternatively, it has been suggested that the name derives from Hur-Muz 'Place of Dates'. Yet another possibility is that it comes from ὅρμος hormos, the Greek word for 'cove, bay'. A theory claims that the strait of Hormuz may have been named after Ifra Hormizd, the mother of King Shapur II of Persia, who ruled between 309 and 379 AD.

The opening to the Persian Gulf was described, but not given a name, in the Periplus of the Erythraean Sea, a 1st-century mariner's guide:

At the upper end of these Calaei islands is a range of mountains called Calon, and there follows not far beyond, the mouth of the Persian Gulf, where there is much diving for the pearl-mussel. To the left of the straits are great mountains called Asabon and to the right there rises in full view another round and high mountain called Semiramis; between them the passage across the strait is about six hundred stadia; beyond which that very great and broad sea, the Persian Gulf, reaches far into the interior. At the upper end of this gulf, there is a market-town designated by law called Apologus, situated near Charaex Spasini and the River Euphrates.

In the 10th–17th centuries AD, the Kingdom of Ormus, which seems to have given the strait its name, was located here. Scholars, historians and linguists derive the name "Ormuz" from the local Persian word هورمغ Hur-mogh meaning date palm. The resemblance of this word to the name of the Zoroastrian god هرمز Hormoz (a variant of Ahura Mazda) has resulted in the belief that these words are related.

Navigation

To reduce the risk of collision, ships moving through the strait follow a traffic separation scheme (TSS): inbound ships use one lane, outbound ships another, each lane being two miles wide. The lanes are separated by a two-mile-wide "median".

To traverse the strait, ships pass through the territorial waters of Iran and Oman under the transit passage provisions of the United Nations Convention on the Law of the Sea. Although not all countries have ratified the convention, most countries, including the U.S., accept these customary navigation rules as codified in the convention.

In 1959, Iran altered the legal status of the strait by expanding its territorial sea to 12 nmi (22 km) and declaring it would recognize only transit by innocent passage through the newly expanded area. In 1972, Oman also expanded its territorial sea to 12 nmi (22 km) by decree. Thus, by 1972, the Strait of Hormuz was completely "closed" by the combined territorial waters of Iran and Oman. During the 1970s, neither Iran or Oman attempted to impede the passage of warships, but in the 1980s, both countries asserted claims that were different from customary (old) law. Upon ratifying UNCLOS in 1989, Oman submitted declarations confirming its 1981 royal decree that only innocent passage is permitted through its territorial sea. The declarations further asserted that prior permission was required before foreign warships could pass through Omani territorial waters. Upon signing the convention in 1982, Iran entered a declaration stating "that only states parties to the Law of the Sea Convention shall be entitled to benefit from the contractual rights created therein", including "the right of transit passage through straits used for international navigation". In 1993, Iran enacted a comprehensive law on maritime areas, provisions of which conflict with UNCLOS provisions, including a requirement that warships, submarines, and nuclear-powered ships obtain permission before exercising innocent passage through Iran's territorial waters. The US does not recognize any of the claims by Oman and Iran and has contested each of them.

Oman has a radar site Link Quality Indicator (LQI) to monitor the TSS in the Strait. This site is on a small island on the peak of Musandam Governorate.

Oil trade flow

During 2023–2025, 20% of the world's liquefied natural gas and 25% of seaborne oil trade passes through the Strait, illustrating its important location for trade.

According to the U.S. Energy Information Administration, in 2011, an average of 14 tankers per day passed out of the Persian Gulf through the strait carrying 17 million barrels (2,700,000 m³) of crude oil. More than 85% of these crude oil exports went to Asian markets, with Japan, India, South Korea and China the largest destinations. In 2018, 21 million barrels a day passed through the strait, worth $1.2 billion at 2019 prices.

Events

Tanker War

The Tanker War phase of the Iran–Iraq War started when Iraq attacked the oil terminal and oil tankers at Iran's Kharg Island in early 1984. Saddam Hussein's aim in attacking Iranian shipping was, among other things, to provoke the Iranians to retaliate with extreme measures, such as closing the Strait of Hormuz to all maritime traffic, thereby bringing American intervention. Iran limited the retaliatory attacks to Iraqi shipping, leaving the strait open.

Operation Praying Mantis

Operation Praying Mantis was an attack on 18 April 1988 by the United States Armed Forces within Iranian territorial waters in retaliation for the Iranian naval mining of international waters in the Persian Gulf during the Iran–Iraq War and the subsequent damage to an American warship. The U.S. Navy attacked with several groups of surface warships, plus aircraft from the aircraft carrier USS Enterprise, and her cruiser escort, USS Truxtun. The attack began with coordinated strikes by two surface groups.

Downing of Iran Air 655

On 3 July 1988, 290 people were killed when an Iran Air Airbus A300 was shot down over the strait by the United States Navy guided missile cruiser USS Vincennes (CG-49) when it was wrongly identified as a jet fighter.

Collisions

In January 2007, the nuclear submarine USS Newport News, struck MV Mogamigawa, a 300,000-ton Japanese-flagged crude tanker, south of the strait. There were no injuries, and no oil leaked. On 20 March 2009, United States Navy Los Angeles-class submarine USS Hartford collided with the San Antonio-class amphibious transport dock USS New Orleans in the strait. The collision ruptured a fuel tank aboard New Orleans, spilling 25,000 US gallons (95 m³) of marine diesel fuel.

Iranian navy problems

In May 2020, Iran launched missiles at one of their own ships in a friendly fire accident, killing 19 sailors. On 2 June 2021, the IRIS Kharg, a modified Ol-class replenishment oiler of the Iran Navy, sank in the Strait of Hormuz after catching fire. It was the navy's largest vessel.

Iranian ship seizures

On 28 April 2015, IRGCN patrol boats contacted the Marshall Islands-flagged container ship Maersk Tigris, which was westbound through the strait, and directed the ship to proceed further into Iranian territorial waters, according to a spokesman for the U.S. Defense Department. When the ship's master declined, one of the Iranian craft fired shots across the bridge of Maersk Tigris. The captain complied and proceeded into Iranian waters near Larak Island. The US Navy sent aircraft and a destroyer, USS Farragut, to monitor the situation. Maersk says it agreed to pay an Iranian company $163,000 after an Iranian court ruling over a dispute about 10 container boxes transported to Dubai in 2005. An appeal court raised the fine to $3.6 million.