The biggest moving objects ever built by man, oil tankers dominate the world's waterways, both in size and numbers. Upwards of 10,000 strong, the world tanker fleet's vast number results from the modern, insatiable thirst for oil. We'll dig into the history of oil transport--from Civil War days to the critical WWII years and invention of the supertanker in the 1950s. And we examine the financial impact of modifying these steel leviathans to prevent future catastrophic environmental disasters.