The average salinity of ocean water is about 35 grams of salt per kilogram of seawater, or 35 parts per thousand (ppt) . This means that in a liter of seawater, there are approximately 35 grams of salt, which is equivalent to about 6 teaspoons of salt. However, the salinity of the ocean varies from place to place, especially at the surface. Much of the ocean has salinity between 34 ppt and 36 ppt, but there are places that tend to be higher or lower. For example, the Mediterranean Sea has very high salinity of 38 ppt or more, while the ocean around Antarctica has a low salinity of just below 34 ppt, and around the Arctic, it is down to 30 ppt in places. The salinity of seawater is affected by various factors such as evaporation, precipitation, riverine inputs, and sea-ice formation, which mostly occur at the surface.