Tip of the iceberg

Interactive of how much of an iceberg is under and over water

The tip of an iceberg which is visible above the waterline is usually only about 1/7 or 1/8 of the mass of an iceberg. Seawater is slightly denser than ice and this means that the iceberg floats with most of its mass below the surface. In comparison a cork, which has a density of about 20% that of water, floats close to the water surface. Ice has about 90% of the density of water but the density of seawater is also influenced by the temperature and salinity.