Look at a map of the world's oil and gas trade and you will see something odd. Most cargo does not spread evenly across the oceans. It squeezes through a handful of narrow passages between continents, islands and peninsulas. Geographers and navies call them chokepoints. A ship that wants to go from the Persian Gulf to Japan, or from Asia to Rotterdam, has very few ways to get there, and each of those ways has a narrow door that someone on the shore can watch.
This guide explains what a chokepoint is, why five of them matter more than the rest, what happened when some of them closed in the past, and how to think about them when you play a strategy game such as Geopolitics.
What makes a sea lane a chokepoint?
A chokepoint is a passage that is narrow, heavily used and hard to replace. All three conditions count. A narrow strait that nobody needs is a local curiosity. A busy lane with an easy alternative is a convenience, not a vulnerability. The real chokepoints combine large flows with a detour that is long, expensive or impossible.
The useful question is always the same: if this passage closed tomorrow, what would ships do? Sometimes they can sail around, paying for extra days at sea, extra fuel and higher insurance. Sometimes cargo can be moved by pipeline. Sometimes there is simply no other way out, and the goods stay where they are. These three answers, a detour, a bypass or a cut, decide how much a closure hurts.
The Strait of Hormuz: the door with no detour
Hormuz connects the Persian Gulf with the Gulf of Oman, between Iran to the north and the Musandam peninsula of Oman to the south. It is about 33 kilometres wide at its narrowest, but the shipping lanes in each direction are only about three kilometres wide. According to the U.S. Energy Information Administration, roughly 20 million barrels of oil a day passed through it in the first half of 2025, around a fifth of global consumption, along with a large share of the world's liquefied natural gas, much of it from Qatar.
What makes Hormuz special is that there is no sea route around it. The Gulf is a closed basin. Saudi Arabia can send part of its crude west by pipeline to the Red Sea, and the United Arab Emirates can pump oil to the port of Fujairah outside the strait, but those pipelines carry only a fraction of normal traffic. Kuwait, Qatar and Bahrain have no bypass at all. A closure of Hormuz is therefore not a delay. It removes supply from the market.
The Strait of Malacca: the busiest lane
Malacca runs between the Malay Peninsula and the Indonesian island of Sumatra and links the Indian Ocean with the South China Sea. By volume of oil it is the busiest of all: the EIA counted more than 23 million barrels a day in the first half of 2025, most of it heading to China, Japan and South Korea. Near Singapore, the Phillips Channel narrows to under three kilometres, and shallow water limits the size of the largest tankers.
Unlike Hormuz, Malacca has alternatives. Ships can use the Sunda Strait or the Lombok Strait through Indonesia. Those routes are longer, so a closure would raise freight costs and delivery times rather than make oil disappear. This difference between a cut and a detour is the first thing to understand about any chokepoint.
Suez and Bab el-Mandeb: one route, two doors
The Suez Canal, opened in 1869, connects the Mediterranean with the Red Sea. At the other end of the Red Sea lies Bab el-Mandeb, a strait about 29 kilometres wide between Yemen and the Horn of Africa. Ships travelling between Europe and Asia by this route must pass both. If either is unsafe, the alternative is the long voyage around the Cape of Good Hope, which typically adds one to two weeks.
History offers several lessons here. Egypt's nationalisation of the canal in 1956 triggered the Suez Crisis. After the war of 1967 the canal stayed closed for eight years, until 1975, and the world adapted by building larger tankers for the Cape route. In March 2021 a single grounded container ship, the Ever Given, blocked the canal for six days and held up hundreds of vessels. From late 2023, attacks on merchant ships near Bab el-Mandeb led many shipping lines to avoid the Red Sea altogether. Egypt, which earns billions of dollars a year from canal fees, felt the loss directly, even though its own canal stayed open.
The point for a strategist is that the country that suffers from a closure is not always the one that owns the passage. Traffic can vanish because of danger far away.
The Turkish Straits and the Danish Straits
The Bosphorus and the Dardanelles connect the Black Sea with the Mediterranean. The Bosphorus runs through the middle of Istanbul and is only about 700 metres wide at its narrowest point, with sharp bends that make navigation demanding. Passage is governed by the Montreux Convention of 1936, which guarantees merchant ships free transit in peacetime and gives Turkey special powers over warships. Oil from Kazakhstan and southern Russia leaves through these straits; the Baku-Tbilisi-Ceyhan pipeline offers a partial bypass for Caspian crude.
In northern Europe, the Danish Straits play a similar role for the Baltic Sea. Ships sailing from Baltic ports to the Atlantic must pass between Denmark and Sweden, with the Kiel Canal in Germany as a small alternative. The Panama Canal completes the picture: in 2023 and 2024 a severe drought lowered the lakes that feed its locks and forced restrictions on the number of daily transits, a reminder that weather, not only politics, can close a door.
What happens to prices when a strait closes?
Oil is traded on a global market. When supply disappears in one place, buyers everywhere compete for the remaining barrels, so prices rise for everyone, including countries that never use the closed route. In the short run demand barely falls, because people still need to heat homes, run factories and drive to work. That is why even a modest loss of supply can produce a large jump in price.
Importers pay higher bills. Exporters whose oil still reaches the market enjoy a windfall. Exporters whose oil is trapped behind the closure lose income at the very moment prices are high. Countries that collect canal fees lose that revenue. A single event creates winners and losers across the whole map.
How chokepoints work in Geopolitics
In Geopolitics, the fuel market models seven straits: Hormuz, Malacca, Suez, Bab el-Mandeb, the Danish Straits, the Turkish Straits and the Panama Canal. Their flows are based on EIA figures, and the game cites the source. Each strait follows one of the three logics described above. Closing Hormuz, the Danish Straits or the Turkish Straits cuts supply, with a limited pipeline bypass. Closing Malacca, Suez, Bab el-Mandeb or Panama forces a detour and adds a freight premium.
Oil and gas prices are indices that start at 1. They react to lost supply, move toward their new level over several days and calm down when the strait reopens. Every country's economy and budget feel the result through its real fuel imports and exports: importers lose growth and pay more, exporters with open routes gain, and those stuck behind a closure lose both exports and revenue.
AI governments at war may close a strait on their shore when their enemy depends on it. When another state's closure costs your country enough, you face a decision: release strategic reserves, join an international convoy escort or wait it out. Each choice has a different cost in money, influence and relations.
If you govern a shore state yourself, you can order a closure once your government reaches the fifth state level. It is a powerful lever and an expensive one. Your reputation falls, relations with every state that depends on the strait suffer, and a closure kept for too long is broken by an international naval coalition. The Fuel tab in the energy window shows prices, open and closed straits and who is affected.
Lessons for players
- Before relying on imported fuel, check which straits your supply passes through.
- Treat reserves in the treasury as insurance against a sudden price shock.
- Remember that a closure far away can still hit your budget.
- Use a closure as a last resort; the diplomatic bill arrives immediately.
For the economics behind these shocks, read energy security and fuel markets explained. To see how pressure without ships works, continue with how economic sanctions work. Then open the game, pick a country and look at the map with new eyes: the narrow doors of the world are where strategy begins.
