In mid January 2025 President Trump announced that he wanted to take back control of the Panama Canal. We might ask what this is all about and the part answer is that the US originally built and operated the canal then handed it back to Panama in 1979. Cutting off journeys round south America it accounts for about 30% of US container trade. But the Panama canal is part of a much bigger picture. Over the last 50 years global trade has increased enormously and about 80% of it is by ship: container ships or bulk carriers for oil, gas, iron ore etc. But global maritime trade is not evenly spread across the globe. It follows certain routes, often the shortest ones, between major trading countries. Today, large amounts of oil and gas come from the Persian gulf, vast amounts of consumer goods come from China to the west. And given the worlds geography, to cut off the Cape of Good Hope or Cape horn and other circuitous journeys, most ships are travelling via canals or straits each of which may have strategic implications for control and access. This is why President Trump wants the Panama canal back under American control, why the Chinese are concerned about the Straits of Malacca and why almost everyone is concerned to keep the Suez canal and the straits of Hormuz open for navigation. Geography matters a lot for world trade.