The vessels, filled with oil worth around $7.5bn at current market prices, would stretch for over 20 nautical miles if formed up in one straight line.
One captain with more than 20 years at sea said his tanker had been anchored off Qingdao in northeastern China since late March and was unlikely to dock before the end of this week, a frustrating delay of more than three weeks.
The worst congestion is in the Middle East, as ports struggle to cope with soaring output available for export, and in Asia, where many ports have not been upgraded in time to deal with ravenous demand as consumers take advantage of cheap fuel.
