The world's largest cruise ship and its supersized pollution problem

When the gargantuan Harmony of the Seas slips out of Southampton docks on Sunday afternoon on its first commercial voyage, the 16-deck-high floating city will switch off its auxiliary engines, fire up its three giant diesels and head to the open sea. But while the 6,780 passengers and 2,100 crew on the largest cruise ship in the world wave goodbye to England, many people left behind in Southampton say they will be glad to see it go.