The Strait of Hormuz: How It Works, and What Depends On It

At its narrowest point the Strait of Hormuz is twenty-one nautical miles across. Everything that leaves the Persian Gulf by sea goes through it — not most things, everything — and before 2026 that was about 20.9 million barrels of oil a day, a fifth of world petroleum consumption and a quarter of all oil traded by sea (US EIA, first half of 2025).

This film is about how that works, what depends on it, and what happened in 2026 when the thing everyone had agreed would never happen happened anyway.

The mechanism first. Two shipping lanes two miles wide with a two-mile buffer between them — a working width of six miles. No international water anywhere in the strait, because it is narrower than the combined territorial seas either side, so every ship is inside somebody's territory at every moment. Depths that confine laden tankers to a known channel at a known place. Two incompatible readings of the law: transit passage, which cannot be suspended, against innocent passage, which can. Bypass pipelines that could carry about 4.7 million barrels a day against 20.9 going through — just over a fifth. And Qatar, whose LNG has no bypass at all, because you cannot decant a cryogenic cargo into a crude line.

Then the forty-year reassurance, and why it was believed: through the Tanker War of the 1980s, with anti-ship missiles used in more than half of all attacks on shipping, Iran never followed through on closing the strait, and disruption never exceeded two per cent of transits.

Then 2026. A VHF warning on 28 February. Tankers struck on 1 and 2 March. Iran declaring the strait closed on the 4th, Qatar declaring force majeure on gas the same day — four days in. And on the 5th, the step that mattered and made the least noise: war-risk insurance was withdrawn. The strait was not sealed by mines. It was sealed by the withdrawal of a piece of paper.

What followed: Brent over $100 on 8 March and peaking near $126, Dubai crude at a record $166; Saudi output cut by a fifth, Iraq declaring force majeure with production down about seventy per cent; roughly 20,000 mariners stranded aboard some 2,000 ships inside the Gulf; 46 documented vessel incidents and 14 seafarers killed. Traffic averaging about five vessels a day from mid-July to late August against 100–140 before the war — an almost 95 per cent decrease. War-risk cover going from 1–3 per cent of hull value to 7.5–10, and a single Gulf-to-China voyage insured for about $21 million against a five-year average nearer $5 million.

Figures last checked 16 September 2026. Every 2026 number carries its date on screen, because this one is still moving.

Not regulated financial advice.

Educational documentary. Not financial or investment advice.