Water has an extremely high specific heat capacity. This means it requires large amounts of energy to increase its temperature, making it a constant environment. When water freezes the structure changes. Hydrogen bonds become fixed holding water molecules slightly further apart making ice less dense. This allows ice to float on the surface insulating the water below meaning organisms can survive during extremely cold conditions. The fact that water is a polar molecule allows it to act as a solvent. Many solutes can freely dissolve into it providing essential compounds and molecules for aquatic life's metabolic processes. Molecules of water have cohesive properties due to its hydrogen bonds, making it move as one mass. There is stronger cohesion between water molecules than there is between water and the air. This creates surface tension allowing small insects to inhabit the surface of the water.