The Strait of Hormuz () is a waterway between the Persian Gulf and the Gulf of Oman. On the north coast lies Iran, and on the south coast lies the Musandam Peninsula under the Musandam Governorate of Oman, with a portion of the southwest of the peninsula under the United Arab Emirates (UAE). The strait is about long, with a width varying from about to .

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. During 2023–2025, 20% of the world's liquefied natural gas and 25% of seaborne oil trade passed through the strait annually. It is a major route of petroleum products for Europe and Asia and is critical for Europe's energy supply. It is also the only maritime route for several Gulf countries including the UAE, Qatar, Bahrain, Kuwait, and Iraq, and disruption to the strait can cause severe supply shortages.

Before the 2026 Iran War, the strait had not been closed for any extended time during Middle East conflicts, although Iran occasionally threatened to close the strait. The closure of the strait caused by Iranian blockades became a major focus during the war, resulting in the 2026 Strait of Hormuz crisis.

Etymology

The origins of the name of Hormuz are vague."Bandar Abbas", Cities of the Middle East and North Africa, Bloomsbury Publishing One theory is the name derives from the local Persian language word Hur-Mogh 'Place of Dates',Municipality of Minab , (in Persian). Retrieved 30 December 2011. while another theory suggests "Hormuz" from the Middle Persian pronunciation of the name of the Zoroastrian god (Ahura Mazda). Some sources suggest the former is more likely,"Hormuz", 1911 Encyclopædia Britannica, page 694 while others lean towards the latter. Another 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. Yet another theory is that it comes from hormos, the Greek word for 'cove, bay'.

Historiography 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:

In the 10th17th centuries AD, the Kingdom of Ormus was located here.

From the 15th century onward, from a strategic point of view, the geography of the strait maintained and expanded its importance with the arrival of foreign powers such as Portugal, which maintained its presence between the 16th and 18th centuries, also provoking disputes with other emerging powers such as England when it arrived in the region in the 17th century.

Geography The Strait of Hormuz is a strait lying between the Persian Gulf and the Gulf of Oman. On the north coast lies Iran, and on the south coast lies the Musandam Peninsula under the Musandam Governorate of Oman, with a portion of the southwest of the peninsula under the United Arab Emirates (UAE). The strait is about long, with a width varying from about to .

Islands Several islands lie within the Strait of Hormuz, including Hormuz Island, Qeshm Island, Larak Island, and Hengam Island. Some of the people living on these islands are descended from enslaved people from Africa. The Naaz islands (also spelt Naz) are joined to Qeshm at low tide, and part of the Qeshm Global Geopark.

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 wide, with the two lanes separated by a similarly wide "median". Commercial ships of countries party to UNCLOS are obliged to follow the TSS during transit passage. The TSS is in Omani territorial waters, however, to the south-east of the strait, very large vessels need to use Iranian waters as alternative waters closer to the United Arab Emirates coastline are relatively shallow.

To traverse the full length of the strait, ships pass through the territorial waters of Iran and Oman. Although Iran has not ratified the UNCLOS convention, most countries, including the U.S. which also has not ratified it, claim the right of passage as codified in the convention.

In 1959, Iran altered the legal status of the strait by expanding its territorial sea to and declaring it would recognize only transit by innocent passage through the newly expanded area. In 1972, Oman also expanded its territorial sea to by decree. Thus, by 1972, the Strait of Hormuz was completely "closed" by the combined territorial waters of Iran and Oman in its narrowest section between the Omani Great Quoin Island and the Iranian Larak Island. In 1971, Iran took over the Greater and Lesser Tunbs islands west of Hormuz against Arab wishes, thereby extending control of the navigation channels.

During the 1970s, neither Iran nor 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 U.S. does not recognize any of the claims by Oman and Iran and has contested each of them.

Trade significance

The Strait of Hormuz 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 is a major route of petroleum products for Europe and Asia and is critical for Europe's energy supply. It is also the only maritime route for several Gulf countries including the UAE, Qatar, Bahrain, Kuwait, and Iraq, and disruption to the strait can cause severe supply shortages.

During 2023–2025, 20% of the world's liquefied natural gas and 25% of seaborne oil trade passed 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 left the Persian Gulf through the strait carrying 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 in 2019 prices.

If shipping through the Strait of Hormuz were significantly disrupted for an extended period, it could lead to a major oil supply crisis for major Asian importers such as Japan, India, South Korea, and China.

The Persian Gulf is also a major hub for global fertilizer production and exports. Countries such as the Islamic Republic of Iran, Qatar, Saudi Arabia, and Oman are among the world's leading exporters of nitrogen fertilizers, including urea and ammonia. In the 2020s the region has accounted for roughly 30–35 percent of global urea exports and around 20%–30% of ammonia exports. Overall, up to 30% of internationally traded fertilizers normally transit the Strait of Hormuz.

Smuggling The Strait of Hormuz is a major route for illicit trade between the Musandam Peninsula, an exclave of Oman, and the southern coast of Iran. The city of Khasab in Musandam is the primary hub for this cross-strait contraband economy. The geographic proximity of the two coastlines, separated by approximately at the strait's narrowest points, allows for the rapid transit of small, high-powered speedboats operated by smugglers.

Goods such as electronics, home appliances, cigarettes, and luxury vehicles are typically purchased in the United Arab Emirates, transported overland to Khasab, and shipped across the strait to evade the international sanctions against Iran. In the opposite direction, Iranian boats transport livestock, primarily sheep and goats destined for markets in the UAE and Saudi Arabia, particularly during Islamic holidays such as Eid al-Adha. Illicit drugs and undocumented migrants are also transported from Iran to Oman.

Omani authorities generally tolerate the trade in Khasab, as it provides a significant source of income for the geographically isolated Musandam region. Conversely, Iranian authorities officially combat the practice. The Iranian Customs and Excise Department has estimated that smuggling across the strait costs the Iranian economy tens of thousands of jobs and circumvents billions of dollars in customs duties annually. The volume of this black market changes depending on the severity of international sanctions on Iran; tighter sanctions increase the demand for smuggled consumer goods in the country. After a reduction of activities towards the end of the Barack Obama presidencies, smuggling has picked up in later years thanks to the intensifying regional conflict.

Events Hormuzian/Portuguese tolls

Tanker War

In May 1981, Iraq began attacking commercial shipping to undermine Iran's war effort. At first, Iraqi forces targeted vessels transporting military supplies to the Iranian ground forces. Later, Iraq expanded the campaign and attacked ships carrying Iranian exports. Iran retaliated by attacking Iraq's trading partners vessels.

In 1984, Iraq broadened the tanker war by attacking the oil terminal and oil tankers at Kharg Island. In response, Iran began attacking tankers traveling to and from Kuwait and other Gulf Arab states that supported Iraq's war effort.

Both sides had declared an "exclusion zone", meaning areas in which they had warned ships from entering. Iraq declared the area around Iran's Kharg Island to be an exclusion zone.

Operation Praying Mantis

Operation Praying Mantis was an attack on 18 April 1988 by the United States Armed Forces against Iranian targets 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 U.S. 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 , a 300,000-ton Japanese-flagged crude oil tanker, south of the strait. There were no injuries and no oil leaked. On 20 March 2009, U.S. Navy collided with the in the strait. The collision ruptured a fuel tank aboard New Orleans, spilling 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