The Danakil Depression was formed by a process that the previous answer named as continental rifting. This is when the earth’s tectonic plates are pulling away from each other, creating a literal sinking of the earth.
However, the Danakil Depression - which is located in a remote area of Ethiopia - also has active volcanoes.
These volcanoes were created through an entirely different process, one where the tectonic plates pushed the land up and created a channel for the magma underneath. With time, the tectonic plates started to shift away from each other, allowing the land to sink while the volcanoes remained active.
This particular wonder of the world is made even more interesting because of the lava, the mud, and the creatures that live there.