Transportation of oil and gas by the Sea characterizes challenges from a safety viewpoint. In this type of transportation, different sizes of special tankers carrying oil and gas. The marine transportation of these scarce natural riches is involved with risks and hazards, which may lead to many losses; for instance, wasting oil and gas, injuries of people, damaging ships and properties, and damaging environment. The main purpose of this thesis is to evaluate the risks, hazards, and accidents during transportation of oil and gas (mainly Crude Oil, liquefied petroleum gas, and Liquefied natural gas) by the Sea with concentrating on transport safety. Hence, a better understanding of these risks and hazards can contribute to decrease of addressed losses.