operator uscgc white alder 
An ocean ( the sea of classical antiquity ) is a body of saline water that composes much of a planet ' s hydrosphere . On Earth , an ocean is one of the major conventional divisions of the World Ocean , which covers almost 71 % of its surface . These are , in descending order by area , the Pacific , Atlantic , Indian , ___MASK75___ ( Antarctic ), and Arctic Oceans . The word " sea " is often used interchangeably with " ocean " in American English but , strictly speaking , a sea is a body of saline water ( generally a division of the world ocean ) partly or fully enclosed by land . ___MASK28___ ( often abbreviated to WWII or WW2 ), also known as the Second World War , was a global war that lasted from 1939 to 1945 , although related conflicts began earlier . It involved the vast majority of the world ' s nations  including all of the great powers  eventually forming two opposing military alliances : the Allies and the Axis . It was the most widespread war in history , and directly involved more than 100 million people from over 30 countries . In a state of " total war ", the major participants threw their entire economic , industrial , and scientific capabilities behind the war effort , erasing the distinction between civilian and military resources . Marked by mass deaths of civilians , including the Holocaust ( in which approximately 11 million people were killed ) and the strategic bombing of industrial and population centres ( in which approximately one million were killed , and which included the atomic bombings of Hiroshima and Nagasaki ), it resulted in an estimated 50 million to 85 million fatalities . These made ___MASK28___ the deadliest conflict in human history . The USCGC White Alder ( WLM / WAGL - 541 ) was the former Navy lighter , YF - 417 . The ___MASK46___ acquired a total of eight of these former Navy YF - 257 - class lighters between 1947 - 1948 for conversion to coastal buoy tenders . They were needed to complement the larger seagoing buoy tenders in servicing short - range - aids - to - navigation , typically those placed in coastal waters and harbors . They were built entirely of steel and were originally designed to carry ammunition and cargo from shore to deep - draft vessels anchored off - shore . These lighters were well suited for a variety of coastal tasks because their hull design incorporated a shallow draft with a solid engineering plant . All of these 133 - foot ( 41 m ) lighters had sufficient cargo space for storing equipment and an open deck and boom for handling large objects . They proved to be capable and useful buoy tenders . Each was named for a plant , shrub or tree , prefixed by `` White . '' A navy or maritime force is a fleet of waterborne military vessels ( watercraft ) and its associated naval aviation , both sea - based and land - based . It is the branch of a nation ' s armed forces principally designated for naval and amphibious warfare ; namely , lake - borne , riverine , littoral , or ocean - borne combat operations and related functions . It includes anything conducted by surface ships , amphibious ships , submarines , and seaborne aviation , as well as ancillary support , communications , training , and other fields ; recent developments have included space - related operations . The strategic offensive role of a navy is projection of force into areas beyond a country ' s shores ( for example , to protect sea - lanes , ferry troops , or attack other navies , ports , or shore installations ). The strategic defensive purpose of a navy is to frustrate seaborne projection - of - force by enemies . The strategic task of the navy also may incorporate nuclear deterrence by use of Submarine - launched ballistic missiles . Naval operations can be broadly divided between riverine and littoral applications ( brown - water navy ), open - ocean applications ( blue - water navy ), and something in between ( green - water navy ), although these distinctions are more about strategic scope than tactical or operational division . A submarine is a watercraft capable of independent operation underwater . It differs from a submersible , which has more limited underwater capability . The term most commonly refers to a large , crewed vessel . It is also sometimes used historically or colloquially to ___MASK79___ to remotely operated vehicles and robots , as well as medium - sized or smaller vessels , such as the midget submarine and the wet sub . Used as an adjective in phrases such as " submarine cable ", " submarine " means " under the sea ". The noun " submarine " evolved as a shortened form of " submarine boat " ( and is often further shortened to " sub "). For reasons of naval tradition , submarines are usually referred to as " boats " rather than as " ships ", regardless of their size . The ___MASK91___ are the federal armed forces of the United States . They consist of the Army , Marine Corps , Navy , Air Force , and Coast Guard . The President of the United States is the military ' s overall head , and helps form military policy with the U . S . Department of Defense ( DoD ), a federal executive department , acting as the principal organ by which military policy is carried out . From the time of its inception , the military played a decisive role in the history of the United States . A sense of national unity and identity was forged as a result of victory in the First Barbary War and the Second Barbary War . Even so , the Founders were suspicious of a permanent military force . It played an important role in the American Civil War , where leading generals on both sides were picked from members of the United States military . Not until the outbreak of World War II did a large standing army become officially established . The National Security Act of 1947 , adopted following World War II and during the Cold War ' s onset , created the modern U . S . military framework ; the Act merged previously Cabinet - level Department of War and the Department of the Navy into the National Military Establishment ( renamed the Department of Defense in 1949 ), headed by the Secretary of Defense ; and created the Department of the Air Force and National Security Council . The term brown - water navy refers in its broadest sense to any naval force capable of military operations in fluvial or littoral environments , especially those carrying heavy sediment loads from soil runoff or flooding . It originated in the ___MASK48___ during the American Civil War , when it referred to Union forces patrolling the muddy Mississippi River , and has since been used to describe the small gunboats and patrol boats commonly used in rivers , along with the larger " mother ships " that supported them . These mother ships include converted World War II - era LCMs and LSTs , among other vessels . The ___MASK46___ ( USCG ) is a branch of the ___MASK91___ and one of the country ' s seven uniformed services . The Coast Guard is a maritime , military , multi - mission service unique among the U . S . military branches for having a maritime law enforcement mission ( with jurisdiction in both domestic and international waters ) and a federal regulatory agency mission as part of its mission set . It operates under the U . S . Department of Homeland Security during peacetime , and can be transferred to the U . S . Department of the Navy by the U . S . President at any time , or by the U . S . Congress during times of war . This has happened twice , in 1917 , during World War I , and in 1941 , during World War II . A blue - water navy is a maritime force capable of operating globally ; essentially across the deep waters of open oceans . A term more often used in the ___MASK69___ to describe such a force is a navy possessing maritime expeditionary capabilities . While definitions of what actually constitutes such a force vary , there is a requirement for the ability to exercise sea control at wide ranges .