For over a century, the Panama Canal has provided a convenient way for ships to move between the Pacific and Atlantic Oceans, helping to speed up international trade.

But a drought has left the canal without enough water, which is used to raise and lower ships, forcing officials to slash the number of vessels they allow through. That has created expensive headaches for shipping companies and raised difficult questions about water use in Panama. The passage of one ship is estimated to consume as much water as half a million Panamanians use in one day.

“This is the worst we have seen in terms of disruption,” said Oystein Kalleklev, the chief executive of Avance Gas, which transports propane from the United States to Asia.

The problems at the Panama Canal, an engineering marvel that opened in 1914 and handles an estimated 5 percent of seaborne trade, is the latest example of how crucial parts of global supply chains can suddenly seize up. In 2021, one of the largest container ships ever built got stuck for days in the Suez Canal, choking off trade. And the huge demand for goods like surgical masks, home appliances and garden equipment during the pandemic strained supply chains to their breaking point.