Classroom lesson ยท Lake Assal ยท ๐Ÿ‡ฉ๐Ÿ‡ฏ Djibouti

Lake Assal

The lowest point in Africa โ€“ and saltier than the Dead Sea!

Photo ยท Wikimedia Commons

What is it?

Lake Assal is a crater lake sitting 155 metres below sea level, making it the lowest point on the entire continent of Africa. It is so salty that thick white crystals form all around its edges, like a giant bathtub ring. In fact it is almost ten times saltier than normal sea water!

Tell me more

If you tossed a handful of salt into a glass of sea water, it would taste about as salty as the ocean. Now imagine doing that ten times over โ€“ that is roughly how salty Lake Assal is. The water is so heavy with salt that you bob up to the surface like a cork and find it almost impossible to sink.

The lake formed inside an old volcano crater, surrounded by dark lava fields that look almost like a moonscape. On sunny days the salt crust glitters brilliant white against the dark rock, and the lake itself shimmers in shades of blue and green depending on the light. There is very little rain here, so water evaporates quickly and the salt is left behind, building up thicker and thicker over thousands of years.

Local people have harvested salt from Lake Assal for a very long time, loading it onto donkeys and camels to sell at markets. Today it is still collected by hand, chipped from the shore in solid blocks. The salt trade was one of Djibouti's earliest businesses and helped connect the country to trading routes across the region.

Because the lake sits so far below sea level and the surrounding land is one of the hottest on Earth, only a few tough creatures survive here. Some bacteria love extremely salty water and tint parts of the lake in pale pink and orange โ€“ like a natural painting.

In the classroom

Walk your class through this in 15 minutes.

Talk together

Discussion prompts

  1. 01If water evaporates and leaves the salt behind, what do you think would happen if you left a saucer of salty water on a sunny windowsill?
  2. 02Why might being very salty make it harder to sink? What does adding salt do to water?
  3. 03Salt from Lake Assal was carried by camels for trading. What things do people trade near where you live?
Try this

Classroom activity

Fill two clear cups with water. Dissolve as much salt as you can into one cup. Then gently lower a small grape into each cup and watch what happens. Draw what you see and write one sentence explaining why the grape behaves differently in each cup.