The Dead Sea, located between Israel and Jordan, is a landlocked lake with a salt concentration so high that it holds no visible life. It has the lowest elevation of any body of water on Earth at more than 400 metres below sea level. It began its formation around 3 million years ago, when Earth’s tectonic plates moved apart beneath the region. This caused a depression in the land, which filled up with seawater as it was connected to the Mediterranean Sea. However, over the next million years, further tectonic activity caused the land to the west of the Dead Sea to lift upwards, separating the Dead Sea from the coastline and turning it into a lake. Being isolated meant that the Dead Sea’s water was now trapped. Water could evaporate out of the basin, but the salt was left behind.
The Jordan River, which connects to the Dead Sea, deposits minerals into the basin. With low rainfall and high evaporation rates, over time the salt level has accumulated and become hypersaline. This means it is much saltier than the other seas, killing any fish, plants and other animals that end up in its waters. In this incredibly salty water, bathing tourists find that they are extremely buoyant. This happens because the salt makes the water much more dense than their bodies and holds them up in the water.