Because a ship is more prone to capsize when it carries less cargo, water is pumped into an unloaded cargo ship to provide stability. This water, serving as a counterweight, is called ballast. Water used as ballast is called ballast water, which is usually taken from coastal port areas. It is concerned that the contained organisms in the ballast water could be non-native species and thus may harm the ecological system of the seawater in the next port of call area when it is discharged.