[Music]
Aquanauts under the volcano
In the calm waters of Lanzarote, the easternmost of the Canary Islands
volcanic rocks are evidence of violent activity on the island in the near geological past.
Thousands of years ago, the volcano of La Corona unleashed its volcanic activity,
resulting in lava flows that extended eastward on the island.
The lava solidified on the surface
while it continued to flow inside, even melting underlying flows,
thus forming a volcanic tube.
The Corona Tunnel extends from the base of the Corona volcano to below sea level,
with a length of approximately ten kilometers.
Along this stretch, there are some windows into the tube itself,
formed by the collapse of its roof.
These openings locally allow us to observe and explore parts of the volcanic tube.
Some of the sections of the tube that can be visited
are the well-known Cueva de los Verdes or the Jameos del Agua complex.
These tourist and cultural centres are known
for being some of the most famous performances of Cesar Manrique and Jesús Soto on the island.
The end of the Corona Tunnel
is known as the Túnel de la Atlántida.
It is a submerged section of the tunnel
with over two kilometers of length
and reaches depths of up to 64 meters below sea level.
The Túnel de la Atlántida was formed approximately 20,000 years ago along with the Corona volcano
when the sea level was around 120 meters lower than it is today.
During the glaciation period, a significant amount of water was trapped in the polar regions
As the ice began to melt and the sea level rose rapidly
it gradually flooded the entire gallery at the end of the Corona Tunnel,
forming this submerged area.
The scientific value of the Túnel de la Atlántida lies not only in its special ecosystem.
The study of its geological, geomorphological and sedimentary elements
will allow us to learn about its evolution from its formation,
when it was generated on land, to its current state,
completely flooded by seawater.
This has been the objective of the research carried out by the Sublántida Project
developed by the UNED in collaboration with other institutions.
Interest in exploring the Túnel de la Atlántida began in 1972,
when the Guerra brothers reached 370 m of development in the main gallery.
Subsequently, several teams of cavedivers completed their exploration,
with the work of the Grupo de Espeleología STD de Madrid standing out,
which in 1985 explored a large part of the cave
up to a length of 1,578 m in the main gallery.
The following year, an international team reached the end of the cave
just 40 m from this point,
making it the largest submerged lava tube in the world.
On one side of Jameos del Agua, you will find Jameo Chico.
This small lake serves as the entry point for all our dives into the Túnel de la Atlántida.
From this little lake,
we access the main gallery, which reaches depths of up to 12 meters.
Here, we can observe a semicircular section
with flow lines and ledges on the sides,
indicating the various stages of lava circulation within the volcanic tube.
Through the passage known as La Sima,
we descend rapidly to a depth of 22 meters,
from where the main gallery continues.
As we advance along it, the blocks of lava scattered on the floor
produced by the retraction of the lava as it cools
become more abundant and partially cover the gallery, forming narrow passages.
From here, access is gained through connections known as windows
to an upper gallery 390 m long
that runs almost parallel to the one below,
at a depth of between 6 and 12 m.
The gallery is gradually reduced in size
and has a characteristic lava floor pavement.
In these dives we can visualise the biological richness of this ecosystem
and understand why it is a world reference.
The anchialine ecosystem of Jameos del Agua and the Túnel de la Atlántida is unique for several reasons
First, because it is almost the only one we know of in this part of the Atlantic,
then because it is also one of the few that is housed in a lava system.
Normally they are in calcium carbonate areas.
And thirdly, because of the number of species it has.
Two important ones to highlight,
because they are also two species protected by the Spanish Government,
is Munidopsis polymorpha, which is the most famous,
it is the jameito, the one you can find on the key rings and stickers that people wear on their cars
And it's important because it's a species that all of its group
live in the deep ocean and this is the only one that lives in caves.
And the second, the remiped, which those of us from Jameos del Agúa call Morlockia,
are the bugs that are most closely related to insects.
Continuing along the main gallery, we further advance
to a depth of 30 meters through a spacious passage.
On the ceiling, we can observe lava stalactites coated with calcium carbonate,
which also forms polygonal blocks caused by the cooling of the lava.
The dating of these stalactites, formed when the volcanic tube was not yet submerged,
has provided an age of 14,000 years when the sea level was 80 meters ower than it is today.
About 550 metres from the entrance we find a new window
that brings us closer to two sections of upper galleries
where we find deposits of marine sands that have been filtering through small cracks
This is the so-called fossil mountain.
A canyon formed by thermal erosion due to the continuous passage of lava
leads us to the Sand Mountain, 700 metres from the entrance
and perhaps the most representative point of the Túnel de la Atlántida.
Through small fissures that connect with the sea floor,
sands and remains of marine fauna have been filtering through,
forming a mound about 12 m high.
The fauna that inhabits this environment differs from that found in the bulk of the water within the tube,
and detailed scientific studies are still pending.
Associated with the influx of nutrients through the fissures,
we find living coral polyps, as well as colonies of fossilized corals
that are 2,000 years old.
These corals formed when the gallery was already completely submerged
due to the rise in sea level.
From this point onwards, the distance to the cave entrance and the depth
require us to use carefully prepared air mixtures
and air recycling systems, which allow us to extend our dives
and enhance safety during the exploration.
When diving in caves, we are always dealing with overhead environments.
It is crucial to plan our gas supply,
allocating a portion for the entrance, another portion for the exit,
and a contingency reserve for emergencies.
This particular cave is approximately 1,700 meters long, and at the end of the tunnel,
it descends to a depth of 64 meters
Therefore, as we approach the end, extensive gas mixtures and meticulous planning
are necessary to ensure safety.
Indeed, the logistics of cave diving were much more challenging 30 years ago.
it appears that access to specialized gas mixtures was limited.
It was a more experimental era in cave diving.
These moments are when we truly appreciate the exploration work
carried out by the pioneering explorers over 30 years ago,
with less sophisticated technical equipment.
Gradually, we continue to progress through the galleries
fully aware that the depth is increasing, and we are more than a kilometer away from the entrance.
Suddenly, a small white spot breaks the monotony of the gallery.
It turns out to be two sand dunes attached to the final wall of the cave.
We are 1,600 meters from the entrance and at a depth of 64 meters.
It has been over 30 years since anyone reached this point.
The studies conducted have allowed us to learn more about the evolution of the Túnel de la Atlántida
After the formation of the volcanic tube of La Corona 21,000 years ago,
its ceilings and walls were adorned with speleothems and other minerals
while it remained in aerial conditions.
Approximately 12,000 years ago, the sea level reached the end of the Tunnel
infiltrating through fissures with sand and shell fragments from the seabed.
The sea level remained stable in this position for a few years due to a global cooling event known as the Younger Dryas.
The sea level rise continued steadily until about 8,200 years ago,
where a temporary pause may have caused desiccation cracks in the fossil mountain sands and silts.
Subsequently, the sea level continued to rise until reaching its current level
approximately 6,500 years ago.
Conducting research in the Túnel de la Atlántida has been a privilege.
Through our geological studies, we have gained understanding
of a portion of the evolution of this unique underwater ecosystem,
solidifying its status as a globally significant geological site.
We are confident that further investigations will unveil the secrets that it still holds.
Space flight is unforgiving. It is inherently dangerous. If you get careless,
it will kill you, more so than most other activities on earth,
except underwater cave exploration.
Dr. James Oberg, Space Engineer, NASA
In memory of José Bedoya "Josefo," explorer of the Túnel de la Atlántida, biologist, and cave diver.