In July 2021, Evergreen Marine took possession of the world's biggest container ship: the Ever Ace. 

Built for Taiwan-based Evergreen Marine, the ship is as long as the Empire State Building is tall from bottom floor to roof. 

With a carrying capacity of 23,992 twenty-foot-equivalent units or TEU, these Evergreen A-class megaships take the record - set just the previous year - from HMM's Algeciras-class ships. 

It can hold 10% more cargo than the infamous Ever Given, that one ship that got stuck in the Suez Canal. 

These ships herald a new era of ultra-large container ships. And it is a bit of a surprising trend. What is pushing these container ships to get bigger? And is there anything keeping them from getting even bigger down the line?