Why are most marine aquariums indoors

How does the salt get into the sea?

Anyone who has ever been to the sea knows: the water tastes salty. Why?

It starts with the rainwater. As it seeps through the earth and flows through streams and rivers, minerals are washed out of sand and stones. There is always a little bit of salt underneath. However, the amount of salt is so small that it is barely measurable, but cannot be tasted.

On the way into the sea, the rivers then wash more salt and other minerals out of the soil. And because all of the world's rivers flow into the sea at some point, a total of several hundred million tons of salt end up in the sea.

Why is the sea salty and the rivers not?

The rivers only supply part of the salt that is in the sea. The other comes from rocks and volcanoes on the ocean floor. When liquid lava escapes under the sea, salts dissolve. Scientists assume that volcanoes and rocks have been releasing salt into the sea for billions of years.

And so the sea is getting salty. When the sun shines on the surface of the sea, the water evaporates, but the salt remains in the sea. So seas are huge salt stores.

Particularly salty: the "Dead Sea"

The “Dead Sea” is particularly salty. Actually, it's not a sea at all, but a huge lake between Israel and Jordan. It is so hot at the Dead Sea that a lot of water evaporates, leaving a lot of salt behind. And because it almost never rains, there is hardly any “fresh” water.

Animals cannot survive in this salt water. That is why it is called the “Dead Sea”. It is even better for people: In the case of skin problems or allergies, the salt from the Dead Sea can be very healing.

In the Dead Sea, bathers can lie comfortably on their backs on the water and read the newspaper - like on an air mattress. The density of the water increases due to the high amount of salt. So the water gets heavier and everything that swims in it is lighter in proportion.