Recently, there have been a number of oil spills that have attracted media attention. In San Francisco Bay, the Cosco Butan hit the Bay Bridge and spilled a quantity of oil. In South Korea, a barge hit the Hedei Spirit and spilled a larger quantity of oil. In the Black Sea, an oil tanker broke apart in a storm and killed a number of birds. All of these accidents have brought to light classifications of oil tankers. The main distinction between the various types is whether or not the tanker has a single hull or a double hull.

Single hull tankers are the older version of oil tankers. Their hull has only one layer of metal and is not reinforced by a second layer. This single layer of hull (the outside of the ship) makes them much more susceptible to oil spills as an object, such as a bridge or land, only needs to pierce one layer of the ship to cause large amounts of oil to flow freely into the ocean or bay. Because of the huge number of spills in the world that have drawn attention to this type of ship, the Exxon Valdez accident involved a single-hulled ship, they are generally viewed in a negative light. To combat this, various countries have tried to create incentives for oil companies to use only double-hulled ships. Also, the International Maritime Organization (IMO) mandated that the single-hulled tankers of the world be taken out of service by 2010. There are still a few exceptions to the rule though.

Double hull tankers are the newer version of oil tankers. Their hulls have two layers, hence the name double hull. This second layer of a hull makes it much more difficult for an object, like a barge, to puncture through to the oil carrying areas of the ship. This, in turn, makes it much more difficult for oil to escape the confines of the ship and leak out into the ocean or any body of water. Double hull tankers are much more expensive than single hull ones which is making oil companies reluctant to switch over. Their point is that there are relatively few oil spill accidents in the world when you consider the number of tankers that are constantly cruising the world's oceans. To combat this, various countries have made the penalties faced if a spill does occur less if the ship involved was double-hulled.

In addition to distinctions made concerning the type of hull a ship has, there are size classifications as well. The size of the ship depends mostly on its carrying capacity. This method was developed by Shell Oil in the 1950s and is called AFRA (Average Freight Rate Assessment). The system is based on creating a range of dead weight tonnage (DWT) for each classification. Many of the oil tankers that have been in the news lately have been Very Large Crude Carriers (VLCC) which means that they have a dead weight tonnage of between 160,000 tons and 319,999 tons. Anything above 319,999 is called an Ultra Large Crude Carrier. The Exxon Valdez was only a Medium Range tanker with a capacity of between 25,000 and 44,999 tons.