Nature, over the years, has created places that are truly magical. One of them is the Sótano de las golondrinas, a natural abyss located in the Teenek mountain range in the state of San Luís Potosí, Mexico. This abyss or basement is, together with the Sótano del mud, the best known in Mexico..
The Sótano de las golondrinas has a total depth of 512 meters, of which 376 are in free fall. Inside it lives the white-collared swift (Streptoprocne zonaris), known locally as swallow.
In recent decades, the chasm has aroused the interest of the most adventurous tourists, since descending into its depths is a unique experience. Let’s get to know a little better how this chasm was formed and its characteristics.
The Formation of the Basement of the Swallows
The Sótano de las golondrinas is a cave of karstic origin —from the German karst, which means ‘limestone plateau’—. It is located in the Sierra Madre Oriental, whose skeleton is formed by this sedimentary limestone rock. Cellars or chasms are characteristic phenomena of these karst landscapes.
These are nothing more than underground cavities, usually cylindrical, whose roof collapsed and collapsed, giving rise to a steeply sloping vertical conduit that gives access to the bowels of the earth.
The basements originate, generally, when the waters of underground rivers stopped flowing or infiltrating to lower levels. This eliminates the pressure that the waters exerted on the ceiling of the cave, which ends up collapsing and collapsing.
This is precisely what happened in the Sótano de las golondrinas. After this process, a cylindrical cavity of about 60 meters in diameter was formed. This entrance to the bowels of the Teenek mountain range is a free fall of 376 meters and has a conical shape. That is to say, as we descend, the cave widens, until reaching 300 meters in diameter at its deepest part.
Once on the ground, we can see the remains of the collapsed roof. On one of the sides of the abyss there is a narrow cavity that descends to 512 meters. Thus, the total depth of the Sótano de las golondrinas is more than half a kilometer.
Even without this narrow grotto, this chasm is impressive, because in it we could enter the Eiffel Tower or one of the most imposing skyscrapers in the world.
Why is the Cellar of the Swallows so called?
As you can imagine, the name comes from the birds that inhabit it. We are talking about a kind of swift that the locals call swallows. We could say that the basement is the dormitory town for thousands of swallows; They go to the jungle at dawn and at nightfall take shelter inside the chasm.
At the time of departure and return, the swallows star in a fascinating show. At the mouth of the chasm a flock of more than 3,000 swallows gathers, flying in a circle. at full speed, waiting their turn to get lost in the jungle or in the bowels of the Earth.
Swallows share this dormitory town with another species of bird, the quila (Aratinga holochlora), also known as the Mexican green parakeet or cave parrot. Both species are protected by the Ministry of the Environment and Natural Resources of Mexico.
When was it discovered?
Officially, the Sótano de las golondrinas was discovered in 1966, when a group of ornithologists from the University of Texas carried out a study of the birds in the region. Although, as you might guess, the chasm had been known for thousands of years by the indigenous Teeneks.
Eight years passed until the first expedition of Mexican scientists was organized. Later, in 1978, the speleology group of the National Autonomous University of Mexico undertook the journey to the bowels of the abyss. Indeed, that was the expedition in which for the first time a woman descended.
Little by little, interest in the cellar ceased to be merely scientific. More and more adventurers wanted to experience the sensation of entering that cave world, to the point that today it is one of the outstanding places where tourists practice speleology.
It must be said that, as a result of this activity, the natural balance of the chasm has been altered and experts are already detecting a decrease in the population of birds that inhabit the Sótano de las golondrinas.
We are going on an adventure to the Sótano de las golondrinas!
As we pointed out, lovers of adventure sports will be able to enjoy the opportunity to descend the more than 300 meters of the Sótano de las golondrinas. It is an unforgettable experience and also very dangerous; For this reason, before entering, the local experts make two test descents in shallower chasms.
This is a requirement to check the physical and mental capacity of the adventurers. Therefore, before traveling to the area, contact the registration booth to reserve a day. It is advisable to go in the dry season, as it is safer; However, if you do not want to descend, during the rainy season it is really beautiful to see how small waterfalls form on the slopes of the chasm.