Let us seek again the concept of density to answer this question. The densities of ice and sea water are so close in value. Remember that the density of ice is 0.92 g/mL, and the density of water is 1.0 g/mL (1.03 for salt water). This means that ice has nine–tenths or 90 percent of water's density roughly. Hence 90% of the iceberg is below the water's surface.
Another explanation can be given in relation to buoyancy. An object is said to be buoyant (floating) if its relative density is less than that of the fluid it is resting in. Hence we can say that ice is buoyant as it has a slightly lower density than seawater. However, due to the negligible difference in relative density between ice and sea water, only some of the iceberg floats above the water. On average only 1/10th of an iceberg is above the surface of the water.
Despite only a fractional part being above the oceanic surface, icebergs pose a danger to ships traversing the North Atlantic and the waters around Antarctica. After the Titanic sank near Newfoundland in 1912, the United States and twelve other countries formed the International Ice Patrol to warn ships of icebergs in the North Atlantic.