Salinity in the oceans varies from about 32 to 37 ppt except in the polar regions and near shore where it may be less than 30 ppt. The average salinity of the world's oceans is 35 ppt, which is the same as 35 grams of salt in each kilogram of water. Approximately 7,500 icebergs are formed during this process each year. Portions of an iceberg may have hues of blue or green, depending upon the age of the iceberg. Glaciers on the west coast of Greenland produce most of the icebergs found in the Northern Hemisphere.
Icebergs vary in size, but are typically irregular with pinnacles.
About seven-eighths of an iceberg is submerged. Thus, iceberg drift is affected more by ocean currents than by wind. When they drift into shipping lanes, they become a serious hazard. A major problem with working at great depths is the tremendous weight of water. Oceans, like the atmosphere, exert pressure on the surface upon which they rest.