Question: why is the sea salty ?

Sakshi Sharda answered on 20 Jun 2014:

Sea is salty for 2 main reasons.

First reason- River water contains contain salts and this flows or drains in the sea making it salty. So what makes the river water contains salts? Well, it’s simple. the water cycle causes evaporation of water from rivers and lakes and causes them to fall back on the earth in the form of rain. When this happens, the rain water leaches out or dissolves some of the salt from the rocks and all this water eventually joins the river. So millions and millions of years of the river draining into the oceans caused the sea water to become salty. However, it is found that for the past many centuries, the concentration of the salt in the sea has remained constant! River water does not taste salty because it is constantly flowing and joining the ocean. However, the ocean has nowhere to drain and the salt eventually gets accumulated.

Second reason- There are many hydrothermal vents on the sea bed. These are small openings on the ocean floor into which the seawater flows. These then recycle the water back into the sea with dissolved salts and minerals.