The presence of salt in seawater affects the freezing point. For that reason, it is possible for seawater to remain in the liquid state at temperatures below melting point. This is "pseudo-supercooling" because the phenomenon is the result of freezing point lowering caused by the presence of salt, not supercooling. This condition is most commonly observed in the oceans around Antarctica where melting of the undersides of ice shelves at high-pressure results in liquid melt-water that can be below the freezing temperature. It is supposed that the water does not immediately refreeze due to a lack of nucleation sites. This provides a challenge to oceanographic instrumentation as ice crystals will readily form on the equipment, potentially affecting the data quality. Ultimately the presence of extremely cold seawater will affect the growth of sea ice.