The normal salinity level is about 3.5% salt for ocean water. What is salinity?
Absolute (or ideal) salinity is the mass fraction of salts in seawater . In practical terms, salinity is expressed as PSU (practical salinity units) which are based on water temperature and conductivity measurements. Salinity used to be expressed in parts per thousand (ppt). For oceanic seawater, ppt and PSU are very close.

Salinity of estuaries usually increases away from a freshwater source such as a river (Figure 1 and 2), although evaporation sometimes causes the salinity at the head of the estuary to exceed seawater. The vertical salinity structure and the nature of salinity variation along the estuary (i.e. how rapidly salinity varies in the vertical and horizontal) are the defining features of the salinity structure of coastal waterways
http://www.ozcoasts.org.au/indicators/salinity.jsp ————– About 70% of the Earth is covered with water, and we find 97% of that water in the oceans. Everyone who has taken in a mouthful of ocean water while swimming knows that the ocean is really salty.
All water has some dissolved material in it. This dissolved material can be solids, liquids or gases that have completely mixed with the water. This dissolved material which can come from the land, precipitation, or the atmosphere, is also referred to as dissolved salts. Dissolved salts are found in river water, groundwater, rain water, lake water, drinking water and so on. Yet, these are all considered fresh water. The difference between fresh water and ocean water is that ocean water contains many more dissolved salts.

Ocean water is about 3.5% salt. That means that if the oceans dried up completely, enough salt would be left behind to build a 180-mile-tall, one- mile-thick wall around the equator. And more than 90 percent of that salt would be sodium chloride, or ordinary table salt.
http://www.windows.ucar.edu/tour/link=/earth/Water/salinity.html&edu=high