The canal authority's figures show a recovery: transits are up a third from the low point of last year, and revenue, which fell by more than half, is climbing back.

The largest container lines have not returned. Routing around the Cape of Good Hope adds about ten days and a great deal of fuel to a voyage between Asia and Europe, and for two years that has been the price of certainty.

Shippers have adjusted. Supply chains that were built around a 30-day transit now assume 40, and inventories have been rebuilt to match. Returning to the canal would require unwinding all of that.

“Our customers have stopped asking when we go back,” said an executive at one of the lines. “That tells you something.”