A mammoth iceberg the size of Rhode Island was sighted off the coast of Antarctica during the summer of 1996. It had apparently split from the coast of East Antarctica a few months earlier. The iceberg, with sheer walls rising 100 to 160 feet above the water line, extends into the water to a depth of 1,000 feet. The huge iceberg, covering more than 1,400 square miles, was first observed by a research ship working with the Antarctic Cooperative Research Center. Sea ice, formed in saltwater, accounts for about 95 percent of ice found in the oceans.
Ice covers about three percent of the world's water surface.
It persists in the Arctic Ocean and around the Antarctica continent throughout the year. New ice growth is greatest during the first year of formation, and attains a thickness of 5 to 6 feet, but has been observed to grow as much as 9 feet in one year. Ice growth depends upon weather and sea conditions. Above normal temperatures, strong winds, or powerful wave action will significantly retard ice formation. Pure water normally freezes at 32 degrees F, but the freezing point of sea water varies considerably.