Are all of the oceans around world salt water?

Yes, all the oceans around the world are salt water. The ocean's salinity is primarily caused by the dissolved salts it contains, such as sodium chloride, magnesium sulfate, calcium carbonate, and potassium sulfate. These salts originate from various sources, including underwater volcanic activity, weathering of rocks on land, and atmospheric deposition. The average salinity of the ocean is approximately 35 parts per thousand (35‰).