Approximately how much of an iceberg is visible above the water?

An iceberg or ice mountain is a large piece of freshwater ice that has broken off a glacier or an ice shelf and is floating freely in open water. It may subsequently become frozen into pack ice (one form of sea ice). As it drifts into shallower waters, it may come into contact with the seabed, a process referred to as seabed gouging by ice. Almost 90% of an iceberg is below the surface of the water.

Because the density of pure ice is about 920 kg/m³, and that of seawater about 1025 kg/m³, typically only one-tenth of the volume of an iceberg is above water (due to Archimedes's Principle). The shape of the underwater portion can be difficult to judge by looking at the portion above the surface. This has led to the expression "tip of the iceberg", for a problem or difficulty that is only a small manifestation of a larger problem.