In spite of being the largest ocean in the world, the Pacific Ocean was not known to the Europeans until the 16th century. When the Spanish explorer, Vasco Núñez de Balboa and his crew crossed the Isthmus of Panama in 1513, they became the first Europeans to navigate the Pacific. In 1521, the Portuguese explorer, Ferdinand Magellan, on his way to become the first person to circumnavigate the Earth, became the first person to cross the Pacific Ocean. While Balboa had named the newly discovered ocean Mar del Sur (Spanish for the 'southern sea'), it was Magellan who called it Mar Pacifico (the 'peaceful sea' in Portuguese), which eventually became the Pacific Ocean. Magellan is believed to have called it so because he noticed that the sea here was a lot more calm than what he had seen in the other parts of the world. The Pacific Ocean extends from the Arctic Ocean in the north to the Southern Ocean in the south. It is bordered by the American continents in the east, and Asia and Australia in the west. The Pacific is linked to the Atlantic Ocean by the Strait of Magellan and Drake Passage, to the Arctic Ocean by the Bering Strait, and to the Indian Ocean by the Strait of Malacca. The equator divides the Pacific into two parts -- the North Pacific and South Pacific. The Pacific, spanning an area of 63.78 million sq mi (165.2 million km²), is the largest ocean in the world. It makes up for a third of the total surface area of the Earth, and half of the planet's water surface. Interestingly, the Pacific is larger than all the continents of the world put together. It stretches for a distance of 11,000 miles at the Equator; that's almost halfway around the Earth. Other than being the largest, the Pacific Ocean also boasts of being the deepest ocean in the world with an average depth in the range of 4028-4188 meters (13,215-13,740 feet). In contrast, the average depth of the oceans on our planet is 3790 meters (12,430 feet). The Pacific basin features some of the deepest ocean trenches in the world, including the Mariana Trench, which is widely considered the deepest point on the Earth. In fact, the 7 deepest ocean trenches in the world are found in the Pacific Ocean. These include the Mariana Trench, Tonga Trench, Kuril-Kamchatka Trench, Philippine Trench, Kermadec Trench, Izu-Ogasawara Trench, and the Japan Trench. While the Mariana Trench is often touted as the deepest point of the Earth, it is actually the deepest 'part' of the world's oceans. Technically, the deepest known point on the planet is the Challenger Deep in the Mariana Trench near Guam, with a depth of 10,994 meters (36,070 feet). At this depth, even Mount Everest, which happens to be tallest structure in the world at 8,848 meters (29,029 feet), will fit inside the Challenger Deep with great ease. There seems to be some confusion about the exact depth of the Challenger Deep with most of the results being in the range of 10,898 to 10,916 meters (some even suggesting a depth in excess of 11,000 meters). However, the reading of 10,994 meters, which was reported by the Center for Coastal and Ocean Mapping (CCOM) in October, 2010, is believed to be the most accurate reading till date. The depth of the Challenger Deep was recorded for the first time during the Challenger expedition of 1872-76. The depression was named after the British Royal Navy survey ship, HMS Challenger, which was used during this expedition. On January 23, 1960, the Trieste research bathyscaphe became the first manned vessel to descend into the Challenger Deep. On March 26, 2012, Canadian filmmaker and deep-sea explorer, James Cameron became the first person to make a solo descend into the Challenger Deep. The Pacific Ocean is also home to the largest coral reef system in the world, the Great Barrier Reef. It occupies an area of 133,000 sq mi off the coast of Queensland, Australia. The reef system has 2900 individual reefs and around 900 islands to its credit. With a length of 1600 miles, it is also considered the longest reef system in the world. The Great Barrier Reef also boasts of being the largest living structure on the planet, and the only one which can be seen from space. There are 25,000 islands in the Pacific Ocean, which is more than all the islands in the other parts of the world put together. These include the islands belonging to the American Samoa, Cook Islands, Hawaii, Guam, the Indonesian archipelago, Solomon Islands, Tahiti, Bora Bora, etc. Most of these islands are found to the south of the Equator in the South Pacific Ocean. The islands in this ocean range from the ones as small as Micronesia and Polynesia, to huge ones, like Taiwan and New Guinea (the largest island in the Pacific Ocean and second largest in the world). A large number of these islands are formed as a result of volcanic activity which is rampant in this region. The Pacific Ocean basin is also characterized by the presence of several volcanoes. In fact, the total number of volcanoes in the periphery of its basin alone account for approximately 75 percent of the total volcanoes in the world. The natural formation of volcanoes along the periphery of the Pacific basin is referred to as the 'Ring of Fire'. Other than the volcanic activity, this region is also prone to earthquakes. In fact, the tectonic movements in the Pacific often trigger destructive gigantic waves known as the tsunamis, which clock the speeds of over 500 mph with ease. The Pacific Ocean also forms an integral part of the global waterways. Several important trade routes lie in this ocean making it one of the busiest oceans in the world. Important ports and harbors of the Pacific include the Sydney Harbor (Australia), Port of Shanghai (China), Port of Hong Kong (China), Port of Singapore (Singapore), Port of Bangkok (Thailand), Port of San Francisco (USA), and the Port of Los Angeles (USA). Of late, the Pacific Ocean has been reduced to a virtual dumping ground, with everything being dumped into it ... literally everything, right from sewage to satellites -- The Upper Atmosphere Research Satellite (UARS) was dumped into the Pacific in 2011. Marine pollution in the Pacific has resulted in formation of the huge garbage patches, like the Great Pacific garbage patch, which is considered the largest landfill in the world. If the same continues abated, we will soon find ourselves at the receiving end, which shouldn't be surprising because the Pacific doesn't just sustain numerous lifeforms, but also sustains several economies.