<P> In the 16th and 17th century Spain considered the Pacific Ocean a Mare clausum--a sea closed to other naval powers . As the only known entrance from the Atlantic the Strait of Magellan was at times patrolled by fleets sent to prevent entrance of non-Spanish ships . On the western end of the Pacific Ocean the Dutch threatened the Spanish Philippines . </P> <P> The 18th century marked the beginning of major exploration by the Russians in Alaska and the Aleutian Islands, such as the First Kamchatka expedition and the Great Northern Expedition, led by the Danish Russian navy officer Vitus Bering . Spain also sent expeditions to the Pacific Northwest reaching Vancouver Island in southern Canada, and Alaska . The French explored and settled Polynesia, and the British made three voyages with James Cook to the South Pacific and Australia, Hawaii, and the North American Pacific Northwest . In 1768, Pierre - Antoine Véron, a young astronomer accompanying Louis Antoine de Bougainville on his voyage of exploration, established the width of the Pacific with precision for the first time in history . One of the earliest voyages of scientific exploration was organized by Spain in the Malaspina Expedition of 1789--1794 . It sailed vast areas of the Pacific, from Cape Horn to Alaska, Guam and the Philippines, New Zealand, Australia, and the South Pacific . </P> <P> Growing imperialism during the 19th century resulted in the occupation of much of Oceania by other European powers, and later, Japan and the United States . Significant contributions to oceanographic knowledge were made by the voyages of HMS Beagle in the 1830s, with Charles Darwin aboard; HMS Challenger during the 1870s; the USS Tuscarora (1873--76); and the German Gazelle (1874--76). </P> <P> In Oceania, France got a leading position as imperial power after making Tahiti and New Caledonia protectorates in 1842 and 1853 respectively . After navy visits to Easter Island in 1875 and 1887, Chilean navy officer Policarpo Toro managed to negotiate an incorporation of the island into Chile with native Rapanui in 1888 . By occupying Easter Island, Chile joined the imperial nations . By 1900 nearly all Pacific islands were in control of Britain, France, United States, Germany, Japan, and Chile . </P>

Where is the pacific and atlantic ocean located