Recently, more attention has been focused on finding and producing oil offshore. One of the first offshore oil rigs was built in 23 feet of water in the Gulf of Mexico in 1947. Because of engineering and technological advances, it is possible to operate in deeper and more hostile waters. We can now build platforms for oil production taller than most of the world's skyscrapers and anchor them to the sea floor in waters deeper than 1300 feet. The larger platforms hold thousands of tons of equipment and can accomodate hundreds of people who work and live there to ensure that oil is produced around the clock.
Oil accounts for almost half of the world's sea trade.
Over land and short distances across the sea, crude oil can be transported by pipeline. For long distance transport by sea, tanker ships are used. At first, oil was transported in wooden barrels on ordinary cargo ships. Hence the term barrel, the unit of measurement for crude oil, where 1 barrel is equal to 42 gallons. Then Marcus Samual adopted the idea of building ships designed to transport only crude oil and oil products which were in effect floating tanks.