Get Used to Oil Tankers Hauling Seawater to America

Supertankers hauling seawater across the Atlantic? That's just one of the odder results of the U.S. shale boom.

Crude oil has always flowed backwards and forwards across the world’s oceans. A typical voyage by one of the global fleet of around 750 of the giant ships currently in service might see it haul Middle Eastern exports across the Atlantic to a refinery on the U.S. Gulf coast, then pick up a cargo from Venezuela for delivery to China or India, before returning to the Persian Gulf.