Ice has about 90% of the density of water but the density of seawater is also influenced by the temperature and salinity. The reason why ice floats and is lighter than water is that a certain mass of ice occupies more space than the same mass of water.

Why does icebergs float on water?

What's so special about ice that causes it to float? Believe it or not, ice is actually about 9% less dense than water. Since the water is heavier, it displaces the lighter ice, causing the ice to float to the top.

How do icebergs actually float?

Because of the dissolved sediments and minerals, sea water is slightly denser than pure water. Its density is approximately 1.03 g/mL. That means that ice (like icebergs) also floats in sea water. In fact, fresh water from melting icebergs will form a layer on top of the denser sea water.