With its cargo of green and orange, rust red and silver grey containers piled high, the Antwerpen Express seems too big to fit inside the locks at Miraflores on the Panama Canal. But under the gentle buffeting of two tug boats, the Hapag Lloyd ship finally slips into place and is lifted upwards to carry on its journey to the Atlantic Ocean.

Within the next decade, however, these locks will be replaced by structures more than twice as large and container liners such as the Antwerpen will be relative minnows, dwarfed by a new generation of mega ships, known in the shipping trade as “post-Panamax”.