The Guelta d'Archei is probably the most famous guelta

Guelta

A guelta is a peculiar type of wetland, typical of desert regions. They are formed when underground water in lowland depressions spills to the surface and creates permanent pools and reservoirs....

 in the Sahara

Sahara

The Sahara is the world's second largest desert, after Antarctica. At over , it covers most of Northern Africa, making it almost as large as Europe or the United States. The Sahara stretches from the Red Sea, including parts of the Mediterranean coasts, to the outskirts of the Atlantic Ocean...

. It is located in the Ennedi Plateau

Ennedi Plateau

The Ennedi Plateau, located in the North-East of Chad, in the Bourkou-Ennedi-Tibesti Region, is a sandstone bulwark in the middle of the Sahara. It is assailed by the sands on all sides, that encroach the deep valleys of the Ennedi...

, in north-eastern Chad

Chad

Chad , officially known as the Republic of Chad, is a landlocked country in Central Africa. It is bordered by Libya to the north, Sudan to the east, the Central African Republic to the south, Cameroon and Nigeria to the southwest, and Niger to the west...

, south-east of the town of Fada

Fada

Fada is the capital of the Ennedi Ouest department of Chad, lying in the Ennedi Plateau. It has a population of 23,786 .It is known for the surrounding cave paintings and rock formations, while the Guelta d'Archei and a wood growing in a wadi are local attractions.It is the birthplace of the...

. The Guelta d'Archei is inhabited by several kinds of animal

Animal

Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...

s, most notably the Nile crocodile

Nile crocodile

The Nile crocodile or Common crocodile is an African crocodile which is common in Somalia, Ethiopia, Uganda, Kenya, Egypt, Tanzania, Zambia, Zimbabwe, Gabon, South Africa, Malawi, Sudan, Botswana, and Cameroon...

 (Crocodylus niloticus Laurenti). Middle Holocene

Holocene

The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...

 remains, as well as rock paintings, indicate that this species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 once thrived across most of today's Sahara Desert

Desert

A desert is a landscape or region that receives an extremely low amount of precipitation, less than enough to support growth of most plants. Most deserts have an average annual precipitation of less than...

 and in swamp

Swamp

A swamp is a wetland with some flooding of large areas of land by shallow bodies of water. A swamp generally has a large number of hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates periodical inundation. The two main types of swamp are "true" or swamp...

s and river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

s along South Mediterranean shores. The small group of surviving crocodile

Crocodile

A crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e...

s in the Guelta d'Archei represent one of the last colonies known in the Sahara today; the Tagant

Tagant

Tagant is a region in south-central Mauritania named for the Tagant Plateau. Its capital is Tidjikdja. Other major cities/towns include Tichit and Rachid, Nbeika...

 hills colony in Mauritania

Mauritania

Mauritania is a country in the Maghreb and West Africa. It is bordered by the Atlantic Ocean in the west, by Western Sahara in the north, by Algeria in the northeast, by Mali in the east and southeast, and by Senegal in the southwest...

has likely been extinct since 1996.

The Guelta d'Archei is a barren place, away from beaten paths: it requires a 4x4 and is at least 4 days travel from n'Djamena, the Chad capital. The place depicted in the picture can only be reached by a few hours trek from the nearest point a 4x4 can approach.