What is the Strait of Hormuz? The complete reference

The Strait of Hormuz is the sea passage that connects the Persian Gulf to the Gulf of Oman and, beyond it, to the Arabian Sea and the open Indian Ocean. It is the only maritime route out of the Gulf. Every barrel of crude and every cargo of liquefied natural gas loaded in Kuwait, Iraq, Iran, Qatar, Bahrain, or on the Gulf coasts of Saudi Arabia and the United Arab Emirates, either passes through it or moves overland — and very little of it moves overland.

At its narrowest the strait is 21 nautical miles across, about 39 km. The usable shipping channel inside that is narrower still: two lanes of two nautical miles each with a two-mile separation zone between them. Those lanes lie inside the territorial waters of Iran and Oman. There is no strip of international water down the middle.

That combination — roughly a fifth of world petroleum liquids consumption moving through a channel a few miles wide, bordered on one side by a state that has repeatedly threatened to close it — is why Hormuz is the most closely watched chokepoint in energy. This guide covers the geography, the traffic separation scheme, the law, who ships what to whom, the bypass options and the military balance, and it ends with a plain answer to the question people actually ask: could Iran close it?

The geography in numbers

Hormuz runs roughly northwest to southeast between the Iranian coast on the north side and the Musandam Peninsula — an exclave of Oman — plus the United Arab Emirates on the south side. The conventional centre point is 26°34′N 56°15′E. The strait is short: a vessel is inside it for hours, not days, which is part of why disruption there is measured in queues and premiums rather than in distance.

• Narrowest point: 21 nautical miles (about 39 km), between Iran and the Musandam Peninsula.
• Shipping channel: two lanes of two nautical miles each, plus a two-mile separation zone between them.
• Depth: the deep-water channel comfortably takes laden VLCCs. Draught has never been the constraint here — width, traffic management and politics are.
• Islands on or near the northern approach: Hormuz, Larak, Qeshm, and the Tunbs and Abu Musa, the last of which are administered by Iran and claimed by the UAE.
• Ports on the approaches: Bandar Abbas and Bandar-e Lengeh on the Iranian side; Khasab in Omani Musandam and Ras al-Khaimah on the southern side; Fujairah sits outside the strait on the Gulf of Oman coast and is the region’s main bunkering and storage hub.
• Transit time: a laden VLCC takes roughly 8 to 12 hours to clear the strait end to end at normal service speed.

The southern shore matters as much as the northern one. Because the lanes at the narrowest point sit in Omani territorial waters off Musandam, Oman is a party to every legal argument about the strait, and Omani mediation has been the route through which most de-escalation has run — including the Muscat memorandum of understanding signed on Jun 24, 2026.

How ships actually transit the strait

Traffic through Hormuz is not a free-for-all. It is organised by a traffic separation scheme adopted through the International Maritime Organization: inbound vessels heading into the Gulf use one lane, outbound vessels use the other, and the separation zone between the two is kept clear. Vessels do not weave. In normal conditions the strait handles on the order of fifty transits a day in both directions combined, and it does so continuously.

The traffic separation scheme

The scheme is the reason a channel this narrow works at all. It converts a crowded two-way waterway into two orderly one-way streams, which is also why interference is so effective: anything that forces vessels out of an assigned lane, or that makes masters distrust the lane they are in, degrades throughput long before a single hull is hit.

1. The vessel reports on approach and joins the assigned lane — inbound from the Gulf of Oman, outbound from the Gulf.
2. Transit proceeds at steady service speed inside that lane. Overtaking is normal; crossing the separation zone is not, except at designated points.
3. Where a flag state, owner or charterer requires it, escorts form up outside the strait and accompany the vessel through the channel.
4. Since the interim memorandum took effect, masters also carry an Iran-designated routing instruction and are expected to acknowledge it before entering the lanes.
5. On clearing the strait the vessel resumes independent navigation for the run to Fujairah, the Arabian Sea, or a discharge berth inside the Gulf.

Who ships what and to whom

Hormuz is often described as an oil chokepoint, which undersells it. It is an oil chokepoint, a condensate and refined-products chokepoint, and — uniquely — an LNG chokepoint, because Qatari LNG has no overland alternative of any kind. The destination mix is heavily Asian: China, India, Japan and South Korea take the large majority of Gulf crude, which is why a Hormuz event is an Asian energy-security event first and a European one second.

The LNG line in that table carries more weight than its crude number suggests. About a fifth of global LNG trade transits Hormuz, and almost all of it is Qatari. Crude has partial workarounds; a molecule of Qatari LNG has none. There is no pipeline, no rail route and no trans-shipment option that moves that cargo out of the Gulf without a ship passing through the strait.

The law of transit passage

The governing framework is the 1982 United Nations Convention on the Law of the Sea. Part III of the convention creates a regime called transit passage for straits used for international navigation that connect one part of the high seas or an exclusive economic zone to another. Hormuz is the textbook case. Transit passage is stronger than the innocent passage that applies in an ordinary territorial sea: it covers submerged submarines and overflight, and — critically — it cannot be suspended by the coastal state.

Ships and aircraft enjoy the right of transit passage, which shall not be impeded.

UNCLOS, Article 38(1)

Iran signed the convention in 1982 but has never ratified it, and it filed an interpretive declaration at signature asserting that transit passage is a contractual right available only to states party. Oman ratified in 1989. The United States has not ratified either, though it treats the navigational provisions as customary international law binding on everyone. The result is a durable stand-off in which each side can cite an instrument the other has not fully accepted.

Why the ratification question matters

In practice this is an argument about legitimacy rather than a switch someone can flip. No coastal state has the legal power to close an international strait, and Iran has never formally claimed that power — its actions have consistently been framed as regulation, inspection, security zones and routing designation, all of which sound like traffic management and function like leverage. The 2026 memorandum follows exactly that shape: Iran concedes fee-free passage and retains the right to say where ships go.

The same logic explains the fate of the alternative-lane idea. In mid-June 2026 the IMO circulated a proposal for a shipping lane off the Omani coast that would have kept traffic clear of Iranian-controlled water. Iran called it void. A lane that exists on paper but is contested in practice is a lane no underwriter will price.

What Iran can actually do

Iranian leverage over Hormuz is a ladder, not a single lever, and almost all of the historical record sits on the lower rungs. The rungs, roughly in order of cost to Iran:

• Announce. Threats alone move war-risk premiums, charter rates and routing decisions, at essentially no cost. The Jun 2025 parliamentary vote recommending closure — never enacted — moved markets by itself.
• Designate and inspect. Lane assignment, boarding and questioning, as under the current memorandum. Slows traffic, damages nothing.
• Seize. Individual detentions are the signature tactic: Stena Impero in Jul 2019, Advantage Sweet and Niovi in 2023, MSC Aries in Apr 2024.
• Jam. GPS jamming and spoofing across the strait has been widespread since Jun 2025 and degrades navigation without a shot being fired.
• Mine. The cheapest persistent option and the hardest to reverse. Mines have been reported in the approach corridors since March 2026, and the mine-clearing initiative floated by France and Oman was rejected in June.
• Strike. Anti-ship missiles, fast attack craft and drones from the Iranian coast and the islands inside the strait. This is the rung that ends the ambiguity — and ends fee-free passage for Iran’s own exports too.

The bypass options

Two pipelines actually move meaningful volumes around the strait, and a third is a recurring headline that has not carried crude for decades. Together they are useful at the margin and nowhere near sufficient in aggregate.

The military balance around a closure

The naval question is not whether the strait can be reopened. It is how long reopening takes, and whether commercial shipping believes the answer. Those are different problems and the second one is slower.

• Mine countermeasures are the pacing item. Clearing a seeded corridor is measured in weeks and months, not days, and it requires the corridor to stay uncontested while the work is done.
• Iranian anti-ship capability is dispersed along a long coastline and across islands inside the strait itself, which makes suppression a campaign rather than a strike package.
• Escorted convoys work and have precedent — Operation Earnest Will ran them for reflagged Kuwaiti tankers in 1987-88 — but they cut throughput, because they impose a schedule on a waterway that normally runs continuously.
• Commercial willingness is the real gate. Hulls move when owners, charterers and war-risk underwriters accept the premium, not when a navy declares a lane open. Traffic recovers on the insurance market’s timetable, not the fleet’s.

Could Iran actually close it

The honest answer has three parts. Iran can make Hormuz effectively unusable for a period — mining plus a handful of strikes would do it, and quickly. Iran cannot hold it closed indefinitely against a sustained clearing effort backed by the states whose economies depend on the route. And Iran has never actually done it, in more than four decades of opportunity, including during the 1984-88 Tanker War, the 2011-12 sanctions confrontation and the 12-day war of Jun 2025.

The reason is that closure is self-harm. Iran’s own crude leaves through the same lanes, overwhelmingly bound for China — the one major buyer that has kept taking it. Closing the strait cuts Iran’s remaining export revenue and antagonises its principal customer at the same time. Restriction, by contrast, is close to free: it extracts leverage, keeps the revenue flowing and stays below the threshold that would justify a clearing operation. That is precisely the posture in force today.

What closure would cost

Pricing a Hormuz event is mostly an exercise in duration. A week of disrupted transits draws down floating and onshore inventory and shows up as a freight and premium shock. A month starts to bite into refinery runs in Asia. A quarter is a different category of problem, because the bypass capacity that exists cannot be expanded on that timescale and the LNG has nowhere to go at all.

The transmission runs through four channels, and they move at different speeds. Crude benchmarks reprice within hours. War-risk premium and freight reprice within days and are the most sensitive early indicator we track on /data. Product cracks follow over weeks. Retail fuel prices, which is where most people actually feel it, lag by several weeks — see /guides/oil-price-scenarios for the crude side and /guides/pump-price for the pass-through.

• Crude flat price: immediate, and typically overshoots the physical shortfall on the first day.
• War-risk premium: quoted as a percentage of hull value per voyage; the cleanest measure of what the market thinks the risk actually is.
• Freight: rates on Gulf-to-Asia routes rise as owners demand compensation for the risk and as voyage times lengthen.
• LNG spot: the thinnest market of the four and the one with no substitute route, which is why it moves hardest on the same headline.

How the 2026 crisis unfolded

1. Feb 28, 2026 — war begins between the United States and Israel and Iran. Iran announces control of the transit lanes. Daily transits fall about 70 per cent and the status level moves to severely restricted.
2. Spring 2026 — mines are reported in the approach corridors. War-risk premiums reprice sharply and several owners suspend Gulf calls outright.
3. Jun 12-20, 2026 — Iran rejects a mine-clearing initiative proposed by France and Oman. The IMO circulates a proposal for an alternative shipping lane off the Omani coast; Iran calls it void.
4. Jun 24, 2026 — a US-Iran memorandum of understanding is signed in Muscat, opening a 60-day fee-free passage window. Iran retains routing designation. The status level improves to restricted.
5. Jul 1, 2026 — a container ship runs aground near Larak Island after transiting a route Iran had not approved. Salvage is under way and both designated lanes remain usable.
6. Jul 5, 2026 — Iranian forces divert six merchant ships from the Omani corridor back into Iran-designated lanes. No damage reported; transit times rise about four hours.

The full event log, running back to the 1984 Tanker War and forward to the current daily brief, is at /timeline. The memorandum itself — what it covers, what it does not, and what happens when the window expires — is broken down in /guides/mou.

Where the situation stands today

As of Jul 7, 2026 the strait is restricted. Ships are transiting under the interim US-Iran agreement, passage is fee-free, and both designated lanes are usable. Iran asserts control over routing, and mines remain a reported hazard in the approach corridors — the two facts that keep this a restricted status rather than an open one.

How to read this site

This site exists to answer one question daily and to show its working. It is an independent status reference, not an advisory service, and it does not tell anyone whether to sail.

• The status banner on the home page at / answers the daily question and nothing else. It is updated around 06:00 UTC.
• /data carries transit counts, war-risk premium quotes and freight rates, refreshed with the daily brief.
• /timeline is the full event log, from the 1984 Tanker War through the current crisis.
• /guides holds the reference articles, including this one, and they are revised whenever the underlying situation changes.
• Every figure carries a source string. Treat all numbers on this site as illustrative sample data and check them against the named source before relying on them.

This guide is revised whenever the status level changes or a material fact in it stops being true. The last substantive revision followed the Jul 5 diversions.