Thermal Capacity is a physical property of matter that determines how much energy needs to be supplied to a substance to raise its temperature. Some things require less energy to raise its temperature than others and this is due to the bonding of the material, or molecules. Water has a high thermal capacity. It requires a lot of energy to raise the temperature of water in comparison to other things in the natural world.
This means that water is able to hold its heat. This makes it a perfect habitat for fish and other aquatic organisms. Living things need a constant temperature and do not cope well with large fluctuations in temperature. During the day a pond is supplied a constant amount of energy from the sun. In the nighttime, when the sun is not present the pond does not drop significantly in temperature as it has a high specific heat capacity and manages to retain its heat.
This is because of the hydrogen bonding network. Unlike other non-polar liquids or things like sand. Hydrogen bonds require more energy to break, therefore in order to raise the temperature of the water. Hydrogen bond network needs to be broken, and therefore requires more energy to raise its temperature.