Located between the continents of North America, South America, Asia, Antarctica and Australia, the Pacific Ocean is the largest of the world's four oceans. It covers approximately one-third of the surface of the earth, more surface area than all the continents combined. It is commonly divided at the Equator into the North Pacific and the South Pacific. The southern portion is dotted with thousands of small volcanic islands and coral atolls (i.e. Fuji, Tahiti). The western rim is lined with large lines of volcanic islands (i.e. Japan, the Philippines). To the north lies the Aleutian Islands- another line of volcanoes- and the Bering Sea. The eastern coast is marked by the Americas.
The tallest mountain in the world is found in the Pacific Ocean: Mauna Kea of the Hawaiian Islands. From the base of the volcano on the ocean floor it is 33,476 feet. That is 4,441 feet higher than Mount Everest. The deepest trench in the world is also housed in the waters of the Pacific. At 36,198 feet deep, the Mariana Trench would submerge Mount Everest with 1.4 miles of water above to spare.
The volcanic regions on the West, North and East rims collectively are known as the Ring of Fire. These areas of volcanic activity are caused by subduction of tectonic plates. In addition to the threat of volcanic eruption, earthquakes are a common occurrence along the Ring of Fire. Many of the earthquakes are among the strongest in the world.
With the threat of earthquakes comes the threat of tsunamis (also incorrectly called tidal waves). These giant waves can travel at speeds of up to 500 miles per hour, appearing as little more than a small wave in the deep sea. Often these waves go undetected by ships they pass beneath.
In the inner regions of the ocean, volcanic islands can also be found. These are either formed over magmatic hot spots or along oceanic rift zones. The Hawaiian chain is over a hot spot. Only the large island of Hawaii is volcanically active. The rest of the islands have moved past the hot spot and drifted off in a north by northwest direction. Remnants of former Hawaiian Islands can be seen as far away as the Aleutian Islands. Much eroded and millions of years old, they are known as the Emperor Seamounts. The oldest of the seamounts are around 70 million years old.