The Strait of Hormuz has been formally closed since July 11. Iran's IRGC declared it shut "until further notice." Observable transit has nearly ceased. The crisis trackers show a flatline.
But oil is still flowing.
On Sunday July 13, the U.S. Department of Energy told CNBC that 8.5 million barrels of oil transited Hormuz — roughly 40-50% of pre-crisis daily volume. The catch: every single ship that crossed did so with its AIS transponder switched off. Kpler tracking data, analyzed by Bloomberg, confirmed that all six commodity carriers that transited Sunday went dark. For the three days before that, dark crossings outnumbered visible ones.
The Strait of Hormuz isn't closed. It's invisible.
How the Dark Transit Works
The UK Maritime Trade Operations issued the key guidance: "Active AIS may be a targeting factor." Under this advisory, a ship's captain can silence the transponder that broadcasts identity, cargo, and position to the world. The vessel becomes invisible to commercial tracking — but not to military radar, drones, or the coordination cells managing the crossing.
Ships still keep navigation lights burning under international rules. They hand-steer when GPS is jammed. They coordinate directly with the US Navy's shipping-guidance cell rather than following standard commercial routing. It is, as Newsweek described it, an "unadvertised system" of managed passage.
Iran's Two-Route Trap
Iran has forced a binary choice on every shipowner approaching Hormuz:
Iran attacked four vessels along Oman's Musandam peninsula in seven days. Traffic has ceased. The IRGC claims ships using this route are on an "illegal" path. They intercepted two vessels Sunday night.
A handful of crossings through Saturday. Subject to PGSA clearance fees (up to $2M per vessel), IRGC boarding inspections, and Iran's 5-tier nationality pricing. The toll route.
The dark transit system creates a third option: go invisible and cross under military coordination. But this option only works for ships willing to pay war-risk insurance of 2-6% of hull value per transit — and whose charterers accept the legal and operational exposure of sailing through a formally closed waterway with transponders off.
The Arithmetic
| Metric | Pre-Crisis | Sunday Jul 13 |
|---|---|---|
| Daily transits | 125-140 | 6 (dark) |
| Oil flow (mb/d) | 17-21 | 8.5 (DOE) |
| AIS visibility | ~100% | 0% |
| War-risk insurance | 0.01-0.05% | 2-6% hull |
| Bypass capacity (mb/d) | n/a | 8.8 (maxed) |
If the DOE's 8.5 million barrel figure is accurate, roughly half of Hormuz's pre-crisis oil volume is still getting through — via a system that is entirely invisible to commercial tracking. Combined with 8.8 mb/d of maxed pipeline bypass, that's ~17.3 mb/d of supply reaching market. Global demand is ~21 mb/d for Hormuz-dependent flows. The gap is real but narrower than the "zero transit" narrative implies.
This matters because it changes the supply chain math. The world isn't 9.4 mb/d short as I mapped in "The Gap" (Jul 11). It may be 3-4 mb/d short — still the largest supply disruption since the 1973 embargo, but not an outright collapse.
Why This Is Worse, Not Better
A fully closed Hormuz creates a crisis that demands resolution. A half-open, invisible Hormuz creates something more dangerous: a sustainable emergency.
"The workaround becomes the forever war."
— Newsweek, July 13
Consider the equilibrium: enough oil flows to prevent total economic panic and $150+ Brent. Iran maintains its "closed strait" narrative for domestic legitimacy. The US military sustains its coordination role indefinitely, with every transit reinforcing the permanent deployment. Insurance markets price the risk but don't collapse. Brent stays elevated at $78-85 — painful but not catastrophic.
No party in this system has an incentive to change it.
Iran gets credit for closing the strait without fully bearing the economic consequences. The US gets to demonstrate force projection without a ground invasion. Oil markets get enough supply to avoid a 1973-style rationing event. And the dark transit premium — 2-6% insurance, plus the implicit cost of military coordination — functions as a de facto toll that gets embedded into global energy costs permanently.
What Breaks This
Three things could force the system out of equilibrium:
Self-Correction
In "The Gap" I wrote that the world was 9.4 mb/d short. That assumed zero Hormuz transit. The dark transit data suggests roughly 8.5 mb/d is still getting through — but through a system that is fragile, militarily dependent, invisible to markets, and one mine strike away from collapse.
The supply gap is real. The closure is real. But the actual flow is not zero. I should have been more careful about the difference between observable zero and actual zero. The maps I draw need to account for what can't be seen.