Ninety percent of all volcanic activity occurs in the oceans. In 1993, scientists located the largest known concentration of active volcanoes on the sea floor in the South Pacific. This area, the size of New York state, hosts 1,133 volcanic cones and sea mounts. Two or three could erupt at any moment. The highest tides in the world are at the Bay of Fundy, which separates New Brunswick from Nova Scotia. At some times of the year the difference between high and low tide is 53 feet 6 inches, the equivalent of a three-story building. The oceans cover 71 percent of the Earth’s surface and contain 97 percent of the Earth’s water. Less than 1 percent is fresh water, and 2-3 percent is contained in glaciers and ice caps. Earth’s longest mountain range is the Mid-Ocean Ridge, which winds around the globe from the Arctic Ocean to the Atlantic, skirting Africa, Asia and Australia, and crossing the Pacific to the west coast of North America. It is four times longer than the Andes, Rockies, and Himalayas combined. Canada has the longest coastline of any country, at 56,453 miles or around 15 percent of the world’s 372,384 miles of coastlines. A slow cascade of water beneath the Denmark Strait sinks 2.2 miles, more than 3.5 times farther than Venezuela’s Angel Falls, the tallest waterfall on land. El Ni–o, a periodic shift of warm waters from the western to eastern Pacific Ocean, has dramatic effects on climate worldwide. In 1982-1983, the most severe El Ni–o of the century created droughts, crop failures, fires, torrential rains, floods, landslides—total damages were estimated at more than $8 billion. At the deepest point in the ocean the pressure is more than 8 tons per square inch, or the equivalent of one person trying to support 50 jumbo jets. At 39 degrees Fahrenheit, the temperature of almost all of the deep ocean is only a few degrees above freezing. If mined, all the gold suspended in the world’s seawater would give each person on Earth 9 pounds. In 1958, the United States Coast Guard icebreaker East Wind measured the world’s tallest known iceberg off western Greenland. At 550 feet it was only 5 feet 6 inches shorter than the Washington Monument in Washington, D.C. Although Mount Everest, at 29,028 feet, is often called the tallest mountain on Earth, Mauna Kea, an inactive volcano on the island of Hawaii, is actually taller. Only 13,796 feet of Mauna Kea stands above sea level, yet it is 33,465 feet tall if measured from the ocean floor to its summit. If the ocean’s total salt content were dried, it would cover the continents to a depth of 5 feet. Undersea earthquakes and other disturbances cause tsunamis, or great waves. The largest recorded tsunami measured 210 feet above sea level when it reached Siberia’s Kamchatka Peninsula in 1737. The Antarctic Ice Sheet is almost twice the size of the United States.