Pacific Ocean

A spring 2000 decision by the International Hydrographic Organization delimited a fifth world ocean from the southern portions of the Atlantic Ocean, Indian Ocean, and Pacific Ocean. The new ocean extends from the coast of Antarctica north to 60 degrees south latitude which coincides with the Antarctic Treaty Limit. The Pacific Ocean remains the largest of the world's five oceans (followed by the Atlantic Ocean, Indian Ocean, Southern Ocean, and Arctic Ocean).

• planetary air pressure systems and resultant wind patterns exhibit remarkable uniformity in the south and east;
• trade winds and westerly winds are well-developed patterns, modified by seasonal fluctuations;
• tropical cyclones (hurricanes) may form south of Mexico from June to October and affect Mexico and Central America;
• continental influences cause climatic uniformity to be much less pronounced in the eastern and western regions at the same latitude in the North Pacific Ocean;
• the western Pacific is monsoonal - a rainy season occurs during the summer months, when moisture-laden winds blow from the ocean over the land, and a dry season during the winter months, when dry winds blow from the Asian landmass back to the ocean;
• tropical cyclones (typhoons) may strike southeast and east Asia from May to December

• surface currents in the northern Pacific are dominated by a clockwise, warm-water gyre (broad circular system of currents) and in the southern Pacific by a counterclockwise, cool-water gyre;
• in the northern Pacific, sea ice forms in the Bering Sea and Sea of Okhotsk in winter;
• in the southern Pacific, sea ice from Antarctica reaches its northernmost extent in October;
• the ocean floor in the eastern Pacific is dominated by the East Pacific Rise, while the western Pacific is dissected by deep trenches, including the Mariana Trench, which is the world's deepest

• surrounded by a zone of violent volcanic and earthquake activity sometimes referred to as the "Pacific Ring of Fire";
• subject to tropical cyclones (typhoons) in southeast and east Asia from May to December (most frequent from July to October);
• tropical cyclones (hurricanes) may form south of Mexico and strike Central America and Mexico from June to October (most common in August and September);
• cyclical El Nino phenomenon occurs off the coast of Peru, when the trade winds slacken and the warm Equatorial countercurrent moves south, killing the plankton that is the primary food source for anchovies;
• consequently, the anchovies move to better feeding grounds, causing resident marine birds to starve by the thousands because of the loss of their food source;
• ships subject to superstructure icing in extreme north from October to May;
• persistent fog in the northern Pacific can be a maritime hazard from June to December

• the major chokepoints are the Bering Strait, Panama Canal, Luzon Strait, and the Singapore Strait;
• the Equator divides the Pacific Ocean into the North Pacific Ocean and the South Pacific Ocean;
• dotted with low coral islands and rugged volcanic islands in the southwestern Pacific Ocean